Upgrade application to Python 3.12 and Django 4.2

[blarghmatey]

Description/Context

This application is years behind in its dependencies, most notably it is still using Django 2.x which has long been out of support. As part of maintaining this project we need to get it running on at least Django 4.2 and update the version of Python being used.

Plan/Design

A substantial amount of this work has been started in the branch here, but it is not yet fully functional.