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>

src/rag/vikingdb_knowledge_base.py

@@ -1,16 +1,18 @@
 # Copyright (c) 2025 Bytedance Ltd. and/or its affiliates
 # SPDX-License-Identifier: MIT
 
-import os
-import requests
-import json
 import hashlib
 import hmac
+import json
+import os
 import urllib.parse
 from datetime import datetime
-from src.rag.retriever import Chunk, Document, Resource, Retriever
 from urllib.parse import urlparse
 
+import requests
+
+from src.rag.retriever import Chunk, Document, Resource, Retriever
+
 
 class VikingDBKnowledgeBaseProvider(Retriever):
     """