chore(deps): update dependency langchain-google-vertexai to v3 (#358)

Co-authored-by: Twisha Bansal <58483338+twishabansal@users.noreply.github.com>

Author: renovate-bot

samples/index_tuning_sample/requirements.txt

@@ -1,3 +1,3 @@
 langchain-community==0.4
 langchain-google-cloud-sql-pg==0.14.1
-langchain-google-vertexai==2.1.2
+langchain-google-vertexai==3.0.0