Bump django-mysql from 3.11.1 to 3.12.0 (#3106)

Bumps [django-mysql](https://github.com/adamchainz/django-mysql) from 3.11.1 to 3.12.0.
- [Release notes](https://github.com/adamchainz/django-mysql/releases)
- [Changelog](https://github.com/adamchainz/django-mysql/blob/main/HISTORY.rst)
- [Commits](adamchainz/django-mysql@3.11.1...3.12.0)

---
updated-dependencies:
- dependency-name: django-mysql
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Dmitry Yakhnov <dmitry@yakhnov.info>

requirements-mysql.txt

@@ -1,2 +1,2 @@
 mysqlclient==2.0.3
-django-mysql==3.11.1
+django-mysql==3.12.0