Set minimum uv version in pyproject.toml

[danielhollas]

This sets the minimum uv version pyproject.toml, which is needed to have a consistent lockfile.
When a dev has an outdated uv version, they'll get an error

❯ uv self update 0.5.19
info: Checking for updates...
success: Upgraded uv from v0.5.20 to v0.5.19! https://github.com/astral-sh/uv/releases/tag/0.5.19
❯ uv lock
error: Required version `>=0.5.20` does not match the running version `0.5.19`

Even better solution for a stable uv version will be to have it in enforced in a pre-commit hook, as in #6699, but that PR is blocked for now.

I've also pinned the setup-uv action to a specific version to prevent accidental regressions since that action is still undergoing heavy development. The new 5.2.0 also allows us to drop a VIRTUAL_ENV workaround. 🎉

Closes #6712

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.00%. Comparing base (7387056) to head (1e05f3e).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #6714   +/-   ##
=======================================
  Coverage   78.00%   78.00%           
=======================================
  Files         563      563           
  Lines       41766    41766           
=======================================
  Hits        32574    32574           
  Misses       9192     9192           

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[danielhollas]

Great to see that all the tests now take less than 20 minutes, well done @unkcpz!

[khsrali]

Thanks @danielhollas LGTM!

[unkcpz]

All good for me as well, thanks.