Add changelog note

Author: henrymercer

CHANGELOG.md

@@ -4,7 +4,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 
 ## [UNRELEASED]
 
-No user facing changes.
+- Bump minimum CodeQL bundle version to 2.17.6. [#3223](https://github.com/github/codeql-action/pull/3223)
 
 ## 4.30.9 - 17 Oct 2025