Switch background task library

[thomersch]

Rationale: We're using django-background-tasks for running asynchronous jobs. This library doesn't get any updates anymore and doesn't seem to support neither Django 4 nor Python 3.12.

Possible solutions:

1. Fork the library and make the necessary changes. It doesn't seem too large, so it might be doable.
2. Swap out for a different library.

Constraints:

1. I don't want to add new infrastructure, it should work with PostgreSQL as backend. (This eliminates Celery)
2. The library shouldn't be too heavy. We don't need many features, just delayed jobs that can be picked up by a worker.
3. Should play somehow nicely with Django without having to write too much additional boilerplate.

[mvexel]

Is this fork an option?

[thomersch]

The fork is definitely an option, but we can also wait for Django DEP-14 to materialise. There is a reference implementation.

The used Django version (3.2) has reached EOL, but it seems that there are no security problems with it so far, so we could stretch it a bit and upgrade only when native background workers are shipped with Django.