Update dev environment to use Python 3.13

[ericziethen]

• [x] Update Django manually first to avoid bigger issues there
• [x] Recreate Requirements to match Python 3.13
• [x] Update Tox testing matrix
• [x] Update CI.yml, use 3.13 and default 3.13 for jobs
• [x] Update documentation of supported packages
• [x] Update setup.py and setup.cfg

[ericziethen]

Looks like Psycogp2/Psycogp2-binary is still waiting for the Windows packages as of today, so can't install yet