CI: use pr target trigger

Author: BenjaminMichaelis

.github/workflows/codeql.yml

@@ -3,8 +3,7 @@ name: "CodeQL"
 on:
   push:
     branches: [ "main" ]
-  pull_request:
-    # The branches below must be a subset of the branches above
+  pull_request_target:
     branches: [ "main" ]
   schedule:
     - cron: '21 15 * * 5'