Update Python to use UV for project managment

[RossSmyth]

Best reviewed by-commit

Update to use uv.

Why:

• It uses venv by default so using and building packages is always project-local
• Has a lock file so you shouldn't get any funny conflicts
• Blazing fast or something idk

I just think it's a more sane way to interact with Python projects.

Things done:

1. Bump minimum Flit to 3.2, this is the recommended (minimum) version by flit devs. Flit 2 has been unmaintained for a while now, and there's no real reason to support it.
2. Use the more modern pyproject.toml layout with a [project] section.
3. Add minimum version for the dev tools. Unsure what this project is using but I put in some values based upon some commit snooping.
4. Update the Makefile to use uv for working with the Python code
5. Update the github workflow to use UV