docs: Update Sample Netflix Application

We change to the proper langchain google vertex ai package.

Co-authored-by: Averi Kitsch <[email protected]>

samples/langchain_quick_start.ipynb

@@ -108,7 +108,7 @@
    "source": [
     "%pip install langchain-google-spanner\n",
     "\n",
-    "%pip install langchain langchain_google_vertexai"
+    "%pip install langchain langchain-google-vertexai"
    ]
   },
   {