Many wheel changes

[AngheloAlf]

Added

• Add support for Python 3.8 again.
  • Figured out how to have CI to test compatibility with Python 3.8 again.
• Wheels for free threaded Python (3.14t).
  • Hopefully nothing will break when running without the GIL.
• Wheels are now tested to be installable in CI.
  • Specifically useful for abi3 wheels, so we can ensure the wheel is
    installable in the oldest Python version we support for each OS/arch combo.
• Integrate uv in CI for Python and dependencies management.

Changed

• Wheels now use the stable abi3 abi instead of building a single wheel for
  each version for GIL Python.
• Python tests in CI are now run against all the Python versions we support
  instead of relying on whatever Python version the Github runner has.
• decomp-settings 0.0.10 is now required.