Update changelog for v4.31.3

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]
+## 4.31.3 - 13 Nov 2025
 
 - CodeQL Action v3 will be deprecated in December 2026.  The Action now logs a warning for customers who are running v3 but could be running v4. For more information, see [Upcoming deprecation of CodeQL Action v3](https://github.blog/changelog/2025-10-28-upcoming-deprecation-of-codeql-action-v3/).
 - Update default CodeQL bundle version to 2.23.5. [#3288](https://github.com/github/codeql-action/pull/3288)