Update changelog for v4.34.0

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]
+## 4.34.0 - 20 Mar 2026
 
 - Added an experimental change which disables TRAP caching when [improved incremental analysis](https://github.com/github/roadmap/issues/1158) is enabled, since improved incremental analysis supersedes TRAP caching. This will improve performance and reduce Actions cache usage. We expect to roll this change out to everyone in March. [#3569](https://github.com/github/codeql-action/pull/3569)
 - We are rolling out improved incremental analysis to C/C++ analyses that use build mode `none`. We expect this rollout to be complete by the end of April 2026. [#3584](https://github.com/github/codeql-action/pull/3584)