Update changelog link

Author: Sephster

CHANGELOG.md

@@ -611,7 +611,7 @@ Version 5 is a complete code rewrite.
 - First major release
 
 [Unreleased]: https://github.com/thephpleague/oauth2-server/compare/8.5.5...HEAD
-[8.5.4]: https://github.com/thephpleague/oauth2-server/compare/8.5.4...8.5.5
+[8.5.5]: https://github.com/thephpleague/oauth2-server/compare/8.5.4...8.5.5
 [8.5.4]: https://github.com/thephpleague/oauth2-server/compare/8.5.3...8.5.4
 [8.5.3]: https://github.com/thephpleague/oauth2-server/compare/8.5.2...8.5.3
 [8.5.2]: https://github.com/thephpleague/oauth2-server/compare/8.5.1...8.5.2