Fix build being skipped

Author: anoadragon453

.github/workflows/docker.yaml

@@ -55,10 +55,10 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
 
       - name: Build and push all platforms
-        if: github.event_name != 'pull_request'
         uses: docker/build-push-action@v4
         with:
-          push: true
+          # Always build, but don't push to container registries on PRs.
+          push: ${{ github.event_name != 'pull_request' }}
           labels: "gitsha1=${{ github.sha }}"
           tags: "${{ steps.set-tag.outputs.tags }}"
           platforms: linux/amd64,linux/arm64