Update server.py

app/server.py

@@ -2,6 +2,7 @@
 """Example LangChain server exposes multiple runnables (LLMs in this case)."""
 
 from fastapi import FastAPI
+from fastapi.responses import RedirectResponse
 from langchain_anthropic import ChatAnthropic
 from langchain_openai import ChatOpenAI
 from langchain_google_genai import ChatGoogleGenerativeAI