Detect running on PR from fork differently

Author: dalito

.github/workflows/test_pages_build.yaml

@@ -16,8 +16,8 @@ permissions: {}
 
 jobs:
   run:
-    # Only run in the canonical repository to avoid failures on forks
-    if: ${{ github.repository == 'nfdi-de/dcat-ap-plus' }}
+    # Don't run for PRs from forks
+    if: github.event.pull_request.head.repo.full_name == github.repository
     # Grant GITHUB_TOKEN the permissions required to make a gh-pages deployment
     permissions:
       contents: write  # to let mkdocs write the new docs