docs: update changelog for version 0.13.0 release

Author: gutzbenj

CHANGELOG.md

@@ -206,7 +206,8 @@ Types of changes:
 - GitHub Actions workflows for CI/CD and releases
 - Use common `defaults` key instead of `global_defaults` and `default_args`
 
-[Unreleased]: https://github.com/ottogroup/koality/compare/v0.12.0...HEAD
+[Unreleased]: https://github.com/ottogroup/koality/compare/v0.13.0...HEAD
+[0.13.0]: https://github.com/ottogroup/koality/compare/v0.12.0...v0.13.0
 [0.12.0]: https://github.com/ottogroup/koality/compare/v0.11.0...v0.12.0
 [0.11.0]: https://github.com/ottogroup/koality/compare/v0.10.0...v0.11.0
 [0.10.0]: https://github.com/ottogroup/koality/compare/v0.9.0...v0.10.0