Update changelog for v3.29.8

Author: github-actions[bot]

CHANGELOG.md

@@ -2,7 +2,7 @@
 
 See the [releases page](https://github.com/github/codeql-action/releases) for the relevant changes to the CodeQL CLI and language packs.
 
-## [UNRELEASED]
+## 3.29.8 - 08 Aug 2025
 
 - Fix an issue where the Action would autodetect unsupported languages such as HTML. [#3015](https://github.com/github/codeql-action/pull/3015)