Skip artifact comment job for fork PRs (#850)

Author: cdc-mitzimorris

.github/workflows/website.yaml

@@ -74,7 +74,7 @@ jobs:
         preview: true
 
   post-page-artifact:
-    if: ${{ github.event_name == 'pull_request' }}
+    if: ${{ github.event_name == 'pull_request' && github.event.pull_request.head.repo.full_name == github.repository }}
     needs: build
     runs-on: ubuntu-latest
     permissions: