xxhash 3.0.0

on Python PyPI

• New set algorithms_available lists all implemented algorithms in xxhash
  package.
• Upgrade xxHash to v0.8.1.
• Drop support for EOL Python versions, require python >= 3.6 from now on.
• Migrate to github actions and build arm64 wheels for macOS.
• Always release GIL.

Full list of changes: v2.0.2...v3.0.0