Add pushing image to GCR in github workflow

Push to GCR in github workflow to faciliate some environments that have rate limitation to docker hub, e.g. vSphere.
 <root@jxun-jumpserver.c.velero-gcp.internal>
Signed-off-by: Xun Jiang <jxun@vmware.com>

.github/workflows/push.yml

@@ -46,3 +46,22 @@ jobs:
       run: |
         docker login -u ${{ secrets.DOCKER_USER }} -p ${{ secrets.DOCKER_PASSWORD }}
         ./hack/docker-push.sh
+
+    - id: 'auth'
+      name: 'Authenticate to Google Cloud'
+      uses: 'google-github-actions/auth@v0.6.0'
+      with:
+        workload_identity_provider: 'projects/298797809281/locations/global/workloadIdentityPools/velero-pool/providers/velero-provider'
+        service_account: 'gcraccount@velero-gcp.iam.gserviceaccount.com'
+
+    - name: Set up gCloud SDK
+      uses: 'google-github-actions/setup-gcloud@v0.5.0'
+
+    - name: Configure docker for GCR
+      run: |
+        gcloud auth configure-docker --quiet
+
+    # Push image to GCR to facilitate some environments that have rate limitation to docker hub, e.g. vSphere.
+    - name: Publish container image to GCR
+      run: |
+        REGISTRY=gcr.io/velero-gcp ./hack/docker-push.sh

changelogs/unreleased/4623-jxun

@@ -0,0 +1 @@
+Add pushing image to GCR in github workflow to facilitate some environments that have rate limitation to docker hub, e.g. vSphere.