0.6.6 - bumped unicode-bidi, replaced macos-12 CI runner

Important Changes since 0.6.3:

• Upgraded to macos-13 runner (as 12 is not available anymore).
• Removed pypy3.8 from build, not supported.
• Bumped pyo3 to 0.23.3, drops pypy3.7 and pypy3.8
• Bumped unicode-bidi to 0.3.18 closes #28