Update app.py

Adding import for VisitWepageTool class

app.py

@@ -11,6 +11,8 @@ import requests
 from bs4 import BeautifulSoup
 import json
 
+from visit_webpage import VisitWebpageTool
+
 # Below is an example of a tool that does nothing. Amaze us with your creativity !
 @tool
 def my_custom_tool(arg1:str, arg2:int)-> str: #it's import to specify the return type