avoid login when in PR (#8449)

.github/workflows/docker.yml

@@ -42,6 +42,7 @@ jobs:
         uses: docker/setup-buildx-action@v1
 
       - name: Login to DockerHub
+        if: ${{ github.event_name != 'pull_request' }}
         uses: docker/login-action@v1
         with:
           username: ${{ secrets.DOCKER_USERNAME }}

.github/workflows/proto-docker.yml

@@ -31,6 +31,7 @@ jobs:
         uses: docker/setup-buildx-action@v1
 
       - name: Login to DockerHub
+        if: ${{ github.event_name != 'pull_request' }}
         uses: docker/login-action@v1
         with:
           username: ${{ secrets.DOCKERHUBTM_USERNAME }}