fix some typo error

app.py

@@ -5,7 +5,7 @@ import pytz
 import yaml
 from tools.final_answer import FinalAnswerTool
 from tools.visit_webpage import VisitWebpageTool
-from tools.web_search import WebSearchTool
+from tools.web_search import DuckDuckGoSearchTool
 
 from Gradio_UI import GradioUI
 
@@ -37,7 +37,7 @@ def get_current_time_in_timezone(timezone: str) -> str:
 
 final_answer = FinalAnswerTool();
 visit_webpage = VisitWebpageTool();
-web_search = WebSearchTool();
+web_search = DuckDuckGoSearchTool();
 
 # If the agent does not answer, the model is overloaded, please use another model or the following Hugging Face Endpoint that also contains qwen2.5 coder:
 # model_id='https://pflgm2locj2t89co.us-east-1.aws.endpoints.huggingface.cloud'