setup django-test-migrations

### Overview

We need a solution to test data migrations automatically. The tool [django-test-migrations](https://github.com/wemake-services/django-test-migrations) offers this possibility but we need to do a trial before we adopt it.

### Action Items

- [ ] Set up [`django-test-migrations`](https://github.com/wemake-services/django-test-migrations)
- [ ] Write tests for existing data migrations (both forward and backward)
- [ ] Check that there's full test coverage of the migration files
- [ ] Create an mkdocs page describing how to use django-test-migrations

### Resources/Instructions

- https://github.com/wemake-services/django-test-migrations
- https://stackoverflow.com/questions/44003620/how-do-i-run-tests-against-a-django-data-migration/59016744#59016744
- [Mkdocs documentation to be updated](https://hackforla.github.io/peopledepot/tools/uv/#upgrade-depencencies)