Refactor settings and run pytest CI in Docker container

[Minnozz]

Pytest should not use the local .env file, even if it is present.

This uses multiple compose files and some environment variables and command line flags to use either .env or .env.example + .env.ci.

Pytest failures should now also appear as annotations on PRs.

Fixes #3308

[Minnozz]

Alternative to #3315 (only one is needed)

[dato]

Hello! And thanks for paying attention to this part of the development setup.

Pytest failures should now also appear as annotations on PRs.

This sounds cool (if it does what I think it does!).

Feel free to merge #3315 instead and close #3316.

Ah, yes, like Hugh, I would also favor going with #3315 for the time being.

072bd3f Don't read .env from within Python

This is a breaking change for non-Docker setups (which don't use EnvironmentFile by default), and any developer who runs pytest or gunicorn directly (they would need to add something like direnv to their setup, I guess?).

This doesn't mean it can't be done, but it introduces churn, plus we'd need updates in documentation and .service files.

As mentioned above, I would suggest we go with #3315 for now (and the use of pytest-github-actions-annotate-failures, if it's easy to introduce on the current version of the workflows?).

[Minnozz]

I'll close #3316 and re-introduce the pytest PR annotations in a separate PR.

[Minnozz]

I re-did this PR in #3318