Update changelog for v2.3.0

Author: github-actions[bot]

CHANGELOG.md

@@ -1,6 +1,6 @@
 # CodeQL Action Changelog
 
-## [UNRELEASED]
+## 2.3.0 - 21 Apr 2023
 
 - Update default CodeQL bundle version to 2.13.0. [#1649](https://github.com/github/codeql-action/pull/1649)
 - Bump the minimum CodeQL bundle version to 2.8.5. [#1618](https://github.com/github/codeql-action/pull/1618)