Add Docker Hub as registry to authenticate with

.github/workflows/vulnerability-comparison.yaml

@@ -33,6 +33,7 @@ jobs:
       - name: Login to Docker Hub
         uses: docker/login-action@v3
         with:
+          registry: ${{ env.REGISTRY }}
           username: ${{ secrets.DOCKERHUB_USERNAME }}
           password: ${{ secrets.DOCKERHUB_TOKEN }}
       - name: Build and push Docker image