feat: Add Python 3.7 Support and Restore Compatibility with Older Syntax

[filipchristiansen]

Summary

• Commit 1: Added Python 3.9 support by:

  • Falling back to ParamSpec from typing_extensions instead of the standard typing module.
  • Refactoring match statements introduced in Python 3.10, reverting them to if/elif blocks for compatibility.

• Commit 2: Extended support further down to Python 3.7 by:

  • Eliminating usage of the walrus operator (:=).
  • Replacing inline generics (e.g., list[str], dict[str, Any]) with the older List[str], Dict[str, Any] style.
  • Updating the required Python version in pyproject.toml and setup.py to >=3.7.
  • Relaxing certain pre-commit checks so that PyUpgrade and others won’t break 3.7 compatibility again.

Details

1. CI Updates: The GitHub Actions matrix now runs tests on Python 3.7, 3.8, 3.9, and all the way up through 3.13, ensuring broad coverage.
2. Documentation: Updated README.md and package classifiers to reflect Python 3.7+ support.
3. No API or Behavior Changes: All modifications are syntax-only to ensure older Python versions can parse and execute the code.