[Task] Upgrade to Django 4

[mradamcox]

Describe the task

Need to get Django upgraded at some point. Currently the platform runs Django 3.2, but that version is well out-of-date.

Additional context

Possibly, this could be paired with a switch to uv for dependency management.

[mradamcox]

I've made all of the necessary code updates in the upgrade_django4 branch.

However, because some of the python lib upgrades need to have python 3.10 or higher, which is not in the apt repository for the current server OS, completing this task would be best combined with a server upgrade as well. Putting on hold for the time being.