jsp: If on a PR, just do a Docker build to make sure we can.

- push only on a tag (which will have the right creds)

#1007

.github/workflows/build-jsp.yml

@@ -95,13 +95,23 @@ jobs:
       with:
         images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
     - name: Build and push Docker image
+      if: github.event_name != 'pull_request'
       id: push
       uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
       with:
         context: UnicodeJsps/
         push: true
         tags: ${{ steps.meta.outputs.tags }}
         labels: ${{ steps.meta.outputs.labels }}
+    - name: Build and Docker image (PR)
+      if: github.event_name == 'pull_request'
+      id: builddocker
+      uses: docker/build-push-action@f2a1d5e99d037542a71f64918e516c093c6f3fc4
+      with:
+        context: UnicodeJsps/
+        push: false
+        tags: ${{ steps.meta.outputs.tags }}
+        labels: ${{ steps.meta.outputs.labels }}
     - name: Generate artifact attestation
       if: github.event_name != 'pull_request'
       uses: actions/attest-build-provenance@v2