What's Changed
* Drop support for Python 3.7/3.8
* Add support for Python 3.13
* Refactoring
* Update copyright years
* Bump sigstore/gh-action-sigstore-python from 2.1.1 to 3.0.0 in the actions-dependencies group by dependabot in https://github.com/thombashi/cleanpy/pull/4
**Full Changelog**: https://github.com/thombashi/cleanpy/compare/v0.5.0...v0.5.1