chore: update .repo-metadata.json (#554)

Author: parthea

packages/google-cloud-pubsub/.repo-metadata.json

@@ -4,12 +4,14 @@
     "product_documentation": "https://cloud.google.com/pubsub/docs/",
     "client_documentation": "https://cloud.google.com/python/docs/reference/pubsub/latest",
     "issue_tracker": "https://issuetracker.google.com/savedsearches/559741",
-    "release_level": "ga",
+    "release_level": "stable",
     "language": "python",
     "repo": "googleapis/python-pubsub",
     "distribution_name": "google-cloud-pubsub",
     "api_id": "pubsub.googleapis.com",
     "requires_billing": true,
     "default_version": "v1",
-    "codeowner_team": "@googleapis/api-pubsub"
+    "codeowner_team": "@googleapis/api-pubsub",
+    "api_shortname": "pubsub",
+    "library_type": ""
 }