Msgfy

- Drop support for Python 3.6
- Add support for Python 3.11
- Update `[build-system]`
- Modify to use `pypa/build` for package build
- Improve error handling
- Improve type annotations

**Full Changelog**: https://github.com/thombashi/msgfy/compare/v0.2.0...v0.2.1

- Add support for Python 3.10
- Drop support for Python 3.5

**Full Changelog**: https://github.com/thombashi/msgfy/compare/v0.1.0...v0.2.0

- Add support for Python 3.9 and PyPy
- Add type annotations and `py.typed` to the package
- Drop Python 2 support
- Remove install_requires
- Remove `build`/`release` extras_require