remove duplicated link

Author: nightkr

crates/stackable-operator/CHANGELOG.md

@@ -21,7 +21,6 @@ All notable changes to this project will be documented in this file.
 [#846]: https://github.com/stackabletech/operator-rs/pull/846
 [#851]: https://github.com/stackabletech/operator-rs/pull/851
 [#855]: https://github.com/stackabletech/operator-rs/pull/855
-[#855]: https://github.com/stackabletech/operator-rs/pull/855
 
 ## [0.74.0] - 2024-08-22