Only run workflow on github/codeql

Author: owen-mc

.github/workflows/label-external-contributions.yml

@@ -13,7 +13,9 @@ concurrency:
 
 jobs:
   label:
-    if: github.ref_name == github.event.repository.default_branch
+    if: >-
+      github.repository == 'github/codeql' &&
+      github.ref_name == github.event.repository.default_branch
     runs-on: ubuntu-latest
     timeout-minutes: 10
     permissions: