feat: 1. replace black with ruff for fomatting and sort import (#489)

2. use tavily from`langchain-tavily` rather than the older one from `langchain-community`

Co-authored-by: Willem Jiang <willem.jiang@gmail.com>

server.py

@@ -10,6 +10,7 @@ import argparse
 import logging
 import signal
 import sys
+
 import uvicorn
 
 # Configure logging