Bump CLI version from v2.21.3 to v2.21.4 for integration tests (#4044)

Co-authored-by: github-actions[bot] <[email protected]>

Author: github-actions[bot]

extensions/ql-vscode/supported_cli_versions.json

@@ -1,5 +1,5 @@
 [
-  "v2.21.3",
+  "v2.21.4",
   "v2.20.7",
   "v2.19.4",
   "v2.18.4",