Update app.py

app.py

@@ -56,7 +56,7 @@ tool = create_retriever_tool(
     "Searches and returns documents regarding the Vanguard website across US and AUS locations. The websites provide investment related information to the user")
 
 tools = [tool]
-llm = ChatOpenAI(temperature=0, streaming=True, model="gpt-4")
+llm = ChatOpenAI(temperature=0, streaming=True, model="gpt-4o")
 message = SystemMessage(
     content=(
         "You are a helpful chatbot who is tasked with answering questions about investments using informationn that has been scraped from a website to answer the users question accurately."