fix: promote library to GA (#201)

* Update .repo-metadata.json

* 🦉 Updates from OwlBot

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>

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

@@ -7,7 +7,7 @@
   "name": "aiplatform",
   "default_version": "v1",
   "client_documentation": "https://cloud.google.com/nodejs/docs/reference/aiplatform/latest",
-  "release_level": "beta",
+  "release_level": "ga",
   "api_id": "aiplatform.googleapis.com",
   "repo": "googleapis/nodejs-ai-platform",
   "codeowner_team": "@googleapis/ml-apis",

packages/google-cloud-aiplatform/README.md

@@ -4,7 +4,7 @@
 
 # [Vertex AI: Node.js Client](https://github.com/googleapis/nodejs-ai-platform)
 
-[![release level](https://img.shields.io/badge/release%20level-beta-yellow.svg?style=flat)](https://cloud.google.com/terms/launch-stages)
+[![release level](https://img.shields.io/badge/release%20level-general%20availability%20%28GA%29-brightgreen.svg?style=flat)](https://cloud.google.com/terms/launch-stages)
 [![npm version](https://img.shields.io/npm/v/@google-cloud/aiplatform.svg)](https://www.npmjs.org/package/@google-cloud/aiplatform)
 [![codecov](https://img.shields.io/codecov/c/github/googleapis/nodejs-ai-platform/main.svg?style=flat)](https://codecov.io/gh/googleapis/nodejs-ai-platform)
 
@@ -187,11 +187,12 @@ _Legacy Node.js versions are supported as a best effort:_
 This library follows [Semantic Versioning](http://semver.org/).
 
 
+This library is considered to be **General Availability (GA)**. This means it
+is stable; the code surface will not change in backwards-incompatible ways
+unless absolutely necessary (e.g. because of critical security issues) or with
+an extensive deprecation period. Issues and requests against **GA** libraries
+are addressed with the highest priority.
 
-This library is considered to be in **beta**. This means it is expected to be
-mostly stable while we work toward a general availability release; however,
-complete stability is not guaranteed. We will address issues and requests
-against beta libraries with a high priority.