PICARD-2192: Build macOS universal2 binaries with ARM64 (Apple Silicon) support

[phw]

Summary

• This is a…
  • Bug fix
  • Feature addition
  • Refactoring
  • Minor / simple change (like a typo)
  • Other
• Describe this change in 1-2 sentences:

Problem

• JIRA ticket (optional): PICARD-2192

This updates the build for macOS to produce universal2 fat binaries, that combine the code for Intel and ARM64 CPUs.

Solution

Specify "universal" as architecture in PyInstaller spec. Use universal2 binaries libdiscid and compile PIP packages PyYAML and charset-normalizer.

TODO:

• The Qt6 binaries are single arch only. We need some solution for this. One option will be to download both the arm64 and x86_64 variants of the PyQt6_Qt6 package from PyPI and combine the binaries locally.
• Qt6 should generally be upgraded to 6.6, as there are some runtime issues with the currently used 6.5 (e.g. global menu does not open). But this is handled in Build with Qt 6.7.0 on windows and macos #2420, but unfortunately there are some CI issues to solve.

Action

Additional actions required:

• Update Picard documentation (please include a reference to this PR)
• Testing on macOS with both Intel and ARM chips