Create locale django.mo files in CI

[asfaltboy]

Is your feature request related to a problem? Please describe.

We can commit django.mo files to the repo, but we might forget to compile to the latest version. We can safeguard against this by always creating the compiled version in all CI steps (build & deploy).

Describe the solution you'd like

Run django-admin compilemessages in github actions.

Describe alternatives you've considered

One alternative could be to require a django.mo file to be committed for every django.po change. This is fragile, however as we have no way of confirming this is the correct result file has been committed (without compiling again and comparing).

Additional context

https://docs.djangoproject.com/en/4.0/topics/i18n/translation/
https://www.hacksoft.io/blog/github-actions-in-action-setting-up-django-and-postgres