Update django to version 4.2

We currently use the version 3.2 of Django which has now finished his mainstream support, but as it's a LTS version, the extended support will last until 2024 so we are safe. However we should consider Django v4.x migration to be ready as fast as possible.

Tasks:

• Migrate to python >= 3.8 (currently v3.7)
• Django update to v4.x
• Pytz -> Zoneinfo migration (Can use USE_DEPRECATED_PYTZ for migration)
• Update redis?
• ...
• Check everything is working

Resources:

• Upgrade version guide
• Changelog
• Deprecation timeline