Add or update CodeQL workflow

Author: mcasimir

.github/workflows/codeql.yml

@@ -14,10 +14,10 @@ name: "CodeQL"
 
 on:
   push:
-    branches: [ "main" ]
+    branches: [ "master" ]
   pull_request:
     # The branches below must be a subset of the branches above
-    branches: [ "main" ]
+    branches: [ "master" ]
   schedule:
     - cron: '30 14 * * 4'