The charm is not handling requirement for pg_trgm extension

The neither charm beta (rev2) or the [current](https://github.com/canonical/ubuntu-com-security-api/commit/7a92843b7de342cd5664b0e685321b6c130d133c) built from source is not working

It requires postgresql-k8s 16/ (no stable branch only beta and edge)

edge postgresql is not starting cluster, I tried adding extra unit but doest not help

```
$ juju status
Model Controller Cloud/Region Version SLA Timestamp
ubuntu-security-api localhost-localhost ck8s/default 3.6.13 unsupported 14:59:19+01:00

App Version Status Scale Charm Channel Rev Address Exposed Message
postgresql-k8s 16.11 waiting 3 postgresql-k8s 16/edge 748 10.152.183.239 no installing agent
ubuntu-security-api blocked 1 ubuntu-security-api 0 10.152.183.55 no missing integrations: postgresql

Unit Workload Agent Address Ports Message
postgresql-k8s/0* waiting executing 10.1.0.54 awaiting for cluster to start
postgresql-k8s/1 unknown idle 10.1.0.3
postgresql-k8s/2 unknown idle 10.1.0.11
ubuntu-security-api/0* blocked idle 10.1.0.186 missing integrations: postgresql
```

when using postgresql-k8s 16 beta charm is failing

```
$ juju status --relations
Model Controller Cloud/Region Version SLA Timestamp
ubuntu-security-api localhost-localhost ck8s/default 3.6.13 unsupported 15:30:58+01:00

App Version Status Scale Charm Channel Rev Address Exposed Message
postgresql-k8s 16.8 active 1 postgresql-k8s 16/beta 525 10.152.183.71 no
ubuntu-security-api blocked 1 ubuntu-security-api 0 10.152.183.150 no database migration command ['bash', '-eo', 'pipefail', 'migrate.sh'] failed, will retry in next update-status

Unit Workload Agent Address Ports Message
postgresql-k8s/0* active idle 10.1.0.169 Primary
ubuntu-security-api/0* blocked idle 10.1.0.22 database migration command ['bash', '-eo', 'pipefail', 'migrate.sh'] failed, will retry in next update-status

Integration provider Requirer Interface Type Message
postgresql-k8s:database ubuntu-security-api:postgresql postgresql_client regular
postgresql-k8s:database-peers postgresql-k8s:database-peers postgresql_peers peer
postgresql-k8s:restart postgresql-k8s:restart rolling_op peer
postgresql-k8s:upgrade postgresql-k8s:upgrade upgrade peer
ubuntu-security-api:secret-storage ubuntu-security-api:secret-storage secret-storage peer
```

The debug-log attached

[ubuntu-security-api_debug-log.log](https://github.com/user-attachments/files/25293775/ubuntu-security-api_debug-log.log)

Start with the attached debug log and the reported failure from migrate.sh, then trace how the charm declares and provisions the pg_trgm PostgreSQL extension. Done means the supported postgresql-k8s deployment completes its migration without blocking the ubuntu-security-api charm.

Written by the indexing model from the issue text.