Prepare release

Author: sebastianbergmann

ChangeLog.md

@@ -2,7 +2,7 @@
 
 All notable changes are documented in this file using the [Keep a CHANGELOG](http://keepachangelog.com/) principles.
 
-## [5.1.0] - 2023-MM-DD
+## [5.1.0] - 2023-12-22
 
 ### Added
 
@@ -124,7 +124,7 @@ All notable changes are documented in this file using the [Keep a CHANGELOG](htt
 
 * This component is no longer supported on PHP 5.6
 
-[5.1.0]: https://github.com/sebastianbergmann/diff/compare/5.0.3...main
+[5.1.0]: https://github.com/sebastianbergmann/diff/compare/5.0.3...5.1.0
 [5.0.3]: https://github.com/sebastianbergmann/diff/compare/5.0.2...5.0.3
 [5.0.2]: https://github.com/sebastianbergmann/diff/compare/5.0.1...5.0.2
 [5.0.1]: https://github.com/sebastianbergmann/diff/compare/5.0.0...5.0.1