Flashfocus

- fixed: Error when .config/flashfocus exists but no config file present
- fixed: Multiple sigints required to terminate flashfocus on sway
- Not user facing:
- Update to use ruff and pre-commit
- Modernize type hints

- Updated: Drop support for python 3.6 and 3.7
- Updated: PEP 517 build system

- Fixed: 78 Fix error when the current workspace is null (fennerm)
- Not user facing: 79 Fixed a bunch of mypy warnings (fennerm)

- Added: 74 pyproject.toml config (Artturin)
- Fixed: 77 Rare race condition when detecting the current workspace (fennerm)
- Fixed: 78 Traceback when the current workspace is null (fennerm)
- Not user facing:
- 74 Misc. code cleanup/ linter fixes (Artturin)
- 75 Fix bug in Dockerfile (Artturin)
- 77 Add github action for running tests and fix some flakey tests (fennerm)
- 76 Add CODEOWNERS file (fennerm)

- Fixed: Relax PyYaml dependency (Artturin)

- Fixed: Remove pytest from setup.py requirements (as it is not really required).