Use uv for various things around CI

[alex]

• [x] uv build for building cryptography sdists + vectors sdists/wheels
  • [x] https://github.com/astral-sh/uv/pull/7085
  • [x] https://github.com/astral-sh/uv/pull/7094
• [x] uv build for building cryptography wheels
  • [x] Linux
    • [x] https://github.com/pypa/manylinux/pull/1670
  • [x] macOS
  • [x] Windows
• [ ] uv pip compile for managing .github/requirements/build-requirements.txt
  • [ ] https://github.com/astral-sh/uv/issues/5190
• [x] uv pip compile for managing .github/requirements/publish-requirements.txt
• [x] uv pip compile for managing ci-constraints-requirements.txt
  • [x] https://github.com/astral-sh/uv/issues/6730
• [x] Pin uv in wheel-builder.yml
• [ ] uv publish in pypi-publish.yml
  • [ ] https://github.com/astral-sh/uv/issues/15618

[alex]

@charliermarsh if you were curious how all the pieces I've been requesting fit together, this is it.