Update pre commit, lint files and fix docs

[mikemanger]

• Switches out various pre-commit tasks to ruff to (fixes Pre-commit tasks not working #37)
• Adds linter job to workflow
• Documentation can be compiled again (fixes Docs not compiling #38)
• Added __str__() definitions for models
• Add Python 3.7 and 3.12 to the classifiers
• Remove unsupported Django and Python code
• Update setup guide and use https links
• Use path instead of re_path for most views

I've ported most of the old flake8/black/isort config to ruff and added flake8-django to the linting config. I've run this config on all files which only brought out one minor user facing change: adding __str__() definitions to the models.

The changes are minor so I'm not sure it warrants a new release however it might be good to update the documentation pages as they're currently out of date.