Add item to changelog

Author: semioticrobotic

CHANGELOG.md

@@ -7,6 +7,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+* add `:` character to sign-off trailer to comply with Conventinoal Commits standard [@semioticrobotic](https://github.com/semioticrobotic) [#2196](https://github.com/extrawurst/gitui/issues/2196)
+
 ## [0.26.0+1] - 2024-04-14
 
 **0.26.1**