Update requirements.txt

requirements.txt

@@ -1,6 +1,10 @@
 fastapi==0.78.0
 uvicorn==0.18.2
-langchain==0.0.37
+langchain==0.2.1
+langchain-community==0.2.1
+langchain-core==0.2.1
+langchain-text-splitters==0.2.0
+langsmith==0.1.63
 faiss-cpu==1.7.2
 huggingface-hub==0.10.1
 transformers==4.18.0