also include external repository input

Author: jamesc-grafana

.github/workflows/periodic-zizmor.yaml

@@ -94,4 +94,6 @@ jobs:
         with:
           sarif_file: ./results.sarif
           token: ${{ steps.get-token.outputs.token }}
+          external-repository-token: ${{ steps.get-token.outputs.token }}
           checkout_path: ./target
+          category: zizmor-periodic