Enable codeql for main pull requests

Author: Mab879

.github/workflows/codeql.yml

@@ -5,7 +5,7 @@ on:
     branches: [ 'maint-1.3', 'maint-1.2', 'main' ]
   pull_request:
     # The branches below must be a subset of the branches above
-    branches: [ 'maint-1.3' ]
+    branches: [ 'maint-1.3', 'main' ]
   schedule:
     - cron: '32 17 * * 0'