Fix an error in the docker workflow (#10461)

.github/workflows/docker.yml

@@ -54,7 +54,7 @@ jobs:
         # we do an amd64-only build, before following up with a multiarch build.
       - name: Build and push amd64
         uses: docker/build-push-action@v2
-        if: "${{ startsWith(github.ref, 'refs/tags/v' }}"
+        if: "${{ startsWith(github.ref, 'refs/tags/v') }}"
         with:
           push: true
           labels: "gitsha1=${{ github.sha }}"