Update gcloud versions (#300)

Update latest gcloud versions

Author: google-github-actions-bot

data/versions.json

@@ -457,5 +457,6 @@
   "503.0.0",
   "504.0.0",
   "504.0.1",
-  "505.0.0"
+  "505.0.0",
+  "506.0.0"
 ]