fix: update dependency to use github over npm

Author: Cloud Shell

generative-ai/snippets/package.json

@@ -14,7 +14,7 @@
   },
   "dependencies": {
     "@google-cloud/aiplatform": "^3.12.0",
-    "@google-cloud/vertexai": "^0.3.1",
+    "@google-cloud/vertexai": "github:googleapis/nodejs-vertexai",
     "axios": "^1.6.2",
     "supertest": "^6.3.3"
   },