Update gb-frontend image in examples guestbook

Use artifact registry url instead gcr as images in gcr are not tagged anymore

Signed-off-by: Praveen Rewar <[email protected]>

examples/gitops/guestbook/all-in-one.yml

@@ -140,7 +140,7 @@ spec:
     spec:
       containers:
       - name: php-redis
-        image: gcr.io/google-samples/gb-frontend:v4
+        image: us-docker.pkg.dev/google-samples/containers/gke/gb-frontend:v5
         resources:
           requests:
             cpu: 100m