feat: promote to ga (#72)

Release-As: 1.0.0

.repo-metadata.json

@@ -4,12 +4,12 @@
   "product_documentation": "https://cloud.google.com/appengine/docs/admin-api/",
   "api_description": "you to manage your App Engine applications.",
   "client_documentation": "https://googleapis.dev/java/google-cloud-appengine-admin/latest/index.html",
-  "release_level": "beta",
+  "release_level": "ga",
   "transport": "grpc",
   "language": "java",
   "repo": "googleapis/java-appengine-admin",
   "repo_short": "java-appengine-admin",
   "distribution_name": "com.google.cloud:google-cloud-appengine-admin",
   "api_id": "appengine.googleapis.com",
   "requires_billing": true
-}
+}