Update CHANGELOG.md for release 6.4.2

Author: fkleedorfer

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+## [6.4.2] - 2024-02-20
+
 ## [6.4.1] - 2024-02-08
 
 ## [6.4.0] - 2024-02-08
@@ -248,7 +250,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Initial release.
 
-[Unreleased]: https://github.com/qudtlib/qudtlib-java/compare/v6.4.1...HEAD
+[Unreleased]: https://github.com/qudtlib/qudtlib-java/compare/v6.4.2...HEAD
+[6.4.2]: https://github.com/qudtlib/qudtlib-java/compare/v6.4.1...v6.4.2
 [6.4.1]: https://github.com/qudtlib/qudtlib-java/compare/v6.4.0...v6.4.1
 [6.4.0]: https://github.com/qudtlib/qudtlib-java/compare/v6.3.0...v6.4.0
 [6.3.0]: https://github.com/qudtlib/qudtlib-java/compare/v6.2.0...v6.3.0