Upgrading from 12.5.2 to 13.3.4 fails with PG::DuplicateColumn migration error

I'm trying to upgrade from 12.5.2 tot 13.3.4. I also updated the Postgres from sameersbn/postgresql:9.6-2 to sameersbn/postgresql:12-20200524, since GitLab 13 requires at least Postgres 11. However, I keep on hitting the following a migration error during start-up.

gitlab_1      | rake aborted!
gitlab_1      | StandardError: An error has occurred, all later migrations canceled:
gitlab_1      | 
gitlab_1      | PG::DuplicateColumn: ERROR:  column "classification" of relation "software_license_policies" already exists
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:92:in `exec'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:92:in `block (2 levels) in execute'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:91:in `block in execute'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:722:in `block (2 levels) in log'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:721:in `block in log'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:712:in `log'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:90:in `execute'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/marginalia-1.8.0/lib/marginalia.rb:71:in `execute_with_marginalia'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/schema_statements.rb:591:in `add_column'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/schema_statements.rb:395:in `add_column'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:890:in `block in method_missing'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:858:in `block in say_with_time'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:858:in `say_with_time'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:879:in `method_missing'
gitlab_1      | /home/git/gitlab/lib/gitlab/database/migration_helpers.rb:1279:in `create_column_from'
gitlab_1      | /home/git/gitlab/lib/gitlab/database/migration_helpers.rb:495:in `rename_column_concurrently'
gitlab_1      | /home/git/gitlab/db/migrate/20191119220425_rename_software_license_policies_approval_status_to_classification.rb:11:in `up'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:831:in `exec_migration'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:812:in `block (2 levels) in migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:811:in `block in migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:471:in `with_connection'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:810:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1002:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1310:in `block in execute_migration_in_transaction'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1363:in `ddl_transaction'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1309:in `execute_migration_in_transaction'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1281:in `block in migrate_without_lock'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1280:in `each'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1280:in `migrate_without_lock'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1229:in `block in migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1382:in `with_advisory_lock'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1229:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1061:in `up'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1036:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/tasks/database_tasks.rb:238:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/railties/databases.rake:86:in `block (3 levels) in <top (required)>'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/railties/databases.rake:84:in `each'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/railties/databases.rake:84:in `block (2 levels) in <top (required)>'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/rake-12.3.3/exe/rake:27:in `<top (required)>'
gitlab_1      | 
gitlab_1      | Caused by:
gitlab_1      | ActiveRecord::StatementInvalid: PG::DuplicateColumn: ERROR:  column "classification" of relation "software_license_policies" already exists
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:92:in `exec'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:92:in `block (2 levels) in execute'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:91:in `block in execute'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:722:in `block (2 levels) in log'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:721:in `block in log'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:712:in `log'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:90:in `execute'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/marginalia-1.8.0/lib/marginalia.rb:71:in `execute_with_marginalia'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/schema_statements.rb:591:in `add_column'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/schema_statements.rb:395:in `add_column'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:890:in `block in method_missing'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:858:in `block in say_with_time'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:858:in `say_with_time'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:879:in `method_missing'
gitlab_1      | /home/git/gitlab/lib/gitlab/database/migration_helpers.rb:1279:in `create_column_from'
gitlab_1      | /home/git/gitlab/lib/gitlab/database/migration_helpers.rb:495:in `rename_column_concurrently'
gitlab_1      | /home/git/gitlab/db/migrate/20191119220425_rename_software_license_policies_approval_status_to_classification.rb:11:in `up'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:831:in `exec_migration'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:812:in `block (2 levels) in migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:811:in `block in migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:471:in `with_connection'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:810:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1002:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1310:in `block in execute_migration_in_transaction'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1363:in `ddl_transaction'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1309:in `execute_migration_in_transaction'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1281:in `block in migrate_without_lock'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1280:in `each'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1280:in `migrate_without_lock'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1229:in `block in migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1382:in `with_advisory_lock'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1229:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1061:in `up'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1036:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/tasks/database_tasks.rb:238:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/railties/databases.rake:86:in `block (3 levels) in <top (required)>'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/railties/databases.rake:84:in `each'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/railties/databases.rake:84:in `block (2 levels) in <top (required)>'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/rake-12.3.3/exe/rake:27:in `<top (required)>'
gitlab_1      | 
gitlab_1      | Caused by:
gitlab_1      | PG::DuplicateColumn: ERROR:  column "classification" of relation "software_license_policies" already exists
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:92:in `exec'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:92:in `block (2 levels) in execute'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/dependencies/interlock.rb:48:in `block in permit_concurrent_loads'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/share_lock.rb:187:in `yield_shares'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/dependencies/interlock.rb:47:in `permit_concurrent_loads'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:91:in `block in execute'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:722:in `block (2 levels) in log'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:26:in `block (2 levels) in synchronize'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `handle_interrupt'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:25:in `block in synchronize'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `handle_interrupt'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/concurrency/load_interlock_aware_monitor.rb:21:in `synchronize'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:721:in `block in log'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activesupport-6.0.3.1/lib/active_support/notifications/instrumenter.rb:24:in `instrument'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract_adapter.rb:712:in `log'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/database_statements.rb:90:in `execute'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/marginalia-1.8.0/lib/marginalia.rb:71:in `execute_with_marginalia'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/schema_statements.rb:591:in `add_column'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/postgresql/schema_statements.rb:395:in `add_column'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:890:in `block in method_missing'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:858:in `block in say_with_time'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:858:in `say_with_time'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:879:in `method_missing'
gitlab_1      | /home/git/gitlab/lib/gitlab/database/migration_helpers.rb:1279:in `create_column_from'
gitlab_1      | /home/git/gitlab/lib/gitlab/database/migration_helpers.rb:495:in `rename_column_concurrently'
gitlab_1      | /home/git/gitlab/db/migrate/20191119220425_rename_software_license_policies_approval_status_to_classification.rb:11:in `up'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:831:in `exec_migration'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:812:in `block (2 levels) in migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:811:in `block in migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/connection_adapters/abstract/connection_pool.rb:471:in `with_connection'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:810:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1002:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1310:in `block in execute_migration_in_transaction'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1363:in `ddl_transaction'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1309:in `execute_migration_in_transaction'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1281:in `block in migrate_without_lock'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1280:in `each'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1280:in `migrate_without_lock'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1229:in `block in migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1382:in `with_advisory_lock'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1229:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1061:in `up'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/migration.rb:1036:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/tasks/database_tasks.rb:238:in `migrate'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/railties/databases.rake:86:in `block (3 levels) in <top (required)>'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/railties/databases.rake:84:in `each'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/activerecord-6.0.3.1/lib/active_record/railties/databases.rake:84:in `block (2 levels) in <top (required)>'
gitlab_1      | /home/git/gitlab/vendor/bundle/ruby/2.6.0/gems/rake-12.3.3/exe/rake:27:in `<top (required)>'
gitlab_1      | Tasks: TOP => db:migrate
gitlab_1      | (See full trace by running task with --trace)

I would appreciate any help.

Start with db/migrate/20191119220425_rename_software_license_policies_approval_status_to_classification.rb and the rename_column_concurrently helper in lib/gitlab/database/migration_helpers.rb. Reproduce the startup migration against the reported PostgreSQL upgrade path and trace the existing classification column state. Done means the 12.5.2-to-13.3.4 migration completes without the duplicate-column error.