Try again to avoid pushing container images in PRs from forks (#31)

* Try again to avoid pushing container images in PRs from forks

* Fix syntax error

Author: ethanjli

.github/workflows/processing-segmenter-build.yml

@@ -74,7 +74,7 @@ jobs:
           labels: ${{ steps.meta.outputs.labels }}
           cache-from: type=gha,scope=build-${{ matrix.platform }}
           cache-to: type=gha,mode=max,scope=build-${{ matrix.platform }}
-          outputs: type=image,name=${{ env.REGISTRY_IMAGE }},push-by-digest=true,name-canonical=true,push=true
+          outputs: type=image,name=${{ env.REGISTRY_IMAGE }},push-by-digest=true,name-canonical=true,push=${{ !github.event.pull_request.head.repo.fork }}
 
       - name: Export digest
         run: |