Update app.py

update：change search engine to BingSearch

app.py

@@ -23,7 +23,7 @@ import os
 os.system("pip show starlette")
 # os.system("pip install -r requirements.txt")
 os.system("pip install tenacity")
-os.system("python -m mindsearch.app --lang en --model_format internlm_silicon --search_engine DuckDuckGoSearch &")
+os.system("python -m mindsearch.app --lang en --model_format internlm_silicon --search_engine BingSearch &")
 
 
 print('MindSearch is running on http://')