Quick fix to the 2.17.4 changelog

Author: coadaflorin

CHANGELOG.md

@@ -77,6 +77,8 @@
 ## Release 2.17.4 (2024-06-03)
 
 - There are no user-facing changes in this release.
+- CodeQL package management is now generally available, and all GitHub-produced
+  CodeQL packages have had their version numbers increased to 1.0.0.
 
 ## Release 2.17.3 (2024-05-17)