chore(external-ssh-signer): add changelog entry

Author: chirpcel

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 * support for "Copy Path" action in WSL [[@johnDeSilencio](https://github.com/johnDeSilencio)] ([#2413](https://github.com/extrawurst/gitui/pull/2413))
 * help popup scrollbar [[@wugeer](https://github.com/wugeer)](https://github.com/extrawurst/gitui/pull/2388))
 * add popups for viewing, adding, updating and removing remotes [[@robin-thoene](https://github.com/robin-thoene)] ([#2172](https://github.com/extrawurst/gitui/issues/2172))
+* add support for ssh comming signing with ssh-agents [[@chirpcel](https://github.com/chirpcel)] ([#2188](https://github.com/extrawurst/gitui/issues/2188))
 
 ## [0.26.3] - 2024-06-02