Consider using uv in our build system

[dae]

It promises considerable performance improvements over things like pip and pip-sync, and seems to have nicer ergonomics.

[dae]

Some reasons why we might not want to:

• No dependabot yet: Support updating uv.lock dependabot/dependabot-core#10478
• uv's creator is apparently relatively new and venture funded, and there's a risk they'll close source or abandon the project in the future

[JeppeKlitgaard]

I have been using uv for all recent projects and it is developing very rapidly and seems to have a lot of momentum. Perhaps my favourite feature is that it will, like rustup, install the correct tooling when running (based on a .python-version file along with dependencies listed in pyproject.toml). I am getting set up for building anki locally and uv would have made this a bit more ergonomic.