Bump CLI version from v2.12.5 to v2.12.6 for integration tests (#2274)

Co-authored-by: github-actions[bot] <github-actions@github.com>

Author: github-actions[bot]

extensions/ql-vscode/supported_cli_versions.json

@@ -1,5 +1,5 @@
 [
-  "v2.12.5",
+  "v2.12.6",
   "v2.11.6",
   "v2.7.6",
   "v2.8.5",