Update gcloud versions (#318)

Update latest gcloud versions

Author: google-github-actions-bot

data/versions.json

@@ -467,5 +467,6 @@
   "512.0.0",
   "513.0.0",
   "514.0.0",
-  "515.0.0"
+  "515.0.0",
+  "516.0.0"
 ]