Update VectorDBQA to RetrievalQA in tools (#3698)

Because `VectorDBQA` and `VectorDBQAWithSourcesChain` are deprecated

langchain/tools/vectorstore/tool.py

@@ -5,8 +5,7 @@ from typing import Any, Dict
 
 from pydantic import BaseModel, Field
 
-from langchain.chains.qa_with_sources.vector_db import VectorDBQAWithSourcesChain
-from langchain.chains.retrieval_qa.base import VectorDBQA
+from langchain.chains import RetrievalQA, RetrievalQAWithSourcesChain
 from langchain.llms.base import BaseLLM
 from langchain.llms.openai import OpenAI
 from langchain.tools.base import BaseTool
@@ -45,12 +44,14 @@ class VectorStoreQATool(BaseVectorStoreTool, BaseTool):
 
     def _run(self, query: str) -> str:
         """Use the tool."""
-        chain = VectorDBQA.from_chain_type(self.llm, vectorstore=self.vectorstore)
+        chain = RetrievalQA.from_chain_type(
+            self.llm, retriever=self.vectorstore.as_retriever()
+        )
         return chain.run(query)
 
     async def _arun(self, query: str) -> str:
         """Use the tool asynchronously."""
-        raise NotImplementedError("VectorDBQATool does not support async")
+        raise NotImplementedError("VectorStoreQATool does not support async")
 
 
 class VectorStoreQAWithSourcesTool(BaseVectorStoreTool, BaseTool):
@@ -71,11 +72,11 @@ class VectorStoreQAWithSourcesTool(BaseVectorStoreTool, BaseTool):
 
     def _run(self, query: str) -> str:
         """Use the tool."""
-        chain = VectorDBQAWithSourcesChain.from_chain_type(
-            self.llm, vectorstore=self.vectorstore
+        chain = RetrievalQAWithSourcesChain.from_chain_type(
+            self.llm, retriever=self.vectorstore.as_retriever()
         )
         return json.dumps(chain({chain.question_key: query}, return_only_outputs=True))
 
     async def _arun(self, query: str) -> str:
         """Use the tool asynchronously."""
-        raise NotImplementedError("VectorDBQATool does not support async")
+        raise NotImplementedError("VectorStoreQAWithSourcesTool does not support async")