Replace You with DDG in xml agent (#12504)

You requires an email to get an API key which IMO is too much friction.
Duckduck go is free and easy to install.

templates/xml-agent/xml_agent/agent.py

@@ -1,14 +1,11 @@
 from typing import List, Tuple
 
 from langchain.agents import AgentExecutor
-from langchain.agents.agent_toolkits.conversational_retrieval.tool import (
-    create_retriever_tool,
-)
 from langchain.agents.format_scratchpad import format_xml
 from langchain.chat_models import ChatAnthropic
 from langchain.pydantic_v1 import BaseModel
-from langchain.retrievers.you import YouRetriever
 from langchain.schema import AIMessage, HumanMessage
+from langchain.tools import DuckDuckGoSearchRun
 from langchain.tools.render import render_text_description
 
 from xml_agent.prompts import conversational_prompt, parse_output
@@ -24,13 +21,8 @@ def _format_chat_history(chat_history: List[Tuple[str, str]]):
 
 model = ChatAnthropic(model="claude-2")
 
-# Fake Tool
-retriever = YouRetriever(k=5)
-retriever_tool = create_retriever_tool(
-    retriever, "search", "Use this to search for current events."
-)
 
-tools = [retriever_tool]
+tools = [DuckDuckGoSearchRun()]
 
 prompt = conversational_prompt.partial(
     tools=render_text_description(tools),