Fix changelog error

Author: Sephster

CHANGELOG.md

@@ -665,7 +665,7 @@ Version 5 is a complete code rewrite.
 - First major release
 
 [Unreleased]: https://github.com/thephpleague/oauth2-server/compare/9.1.0...HEAD
-[9.0.1]: https://github.com/thephpleague/oauth2-server/compare/9.0.1...9.1.0
+[9.1.0]: https://github.com/thephpleague/oauth2-server/compare/9.0.1...9.1.0
 [9.0.1]: https://github.com/thephpleague/oauth2-server/compare/9.0.0...9.0.1
 [9.0.0]: https://github.com/thephpleague/oauth2-server/compare/9.0.0-RC1...9.0.0
 [9.0.0-RC1]: https://github.com/thephpleague/oauth2-server/compare/8.5.4...9.0.0-RC1