Update .github/workflows/wheels.yml

Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>

Author: aclark4life

.github/workflows/wheels.yml

@@ -277,7 +277,10 @@ jobs:
           anaconda_nightly_upload_token: ${{ secrets.ANACONDA_ORG_UPLOAD_TOKEN }}
 
   sbom:
-    if: github.repository_owner == 'python-pillow' && github.event_name == 'push' && startsWith(github.ref, 'refs/tags')
+    if: |
+      github.event.repository.fork == false
+      && github.event_name == 'push'
+      && startsWith(github.ref, 'refs/tags')
     needs: count-dists
     runs-on: ubuntu-latest
     name: Generate and publish SBOM