Update app.py

Modifed approach to calling DuckDuckGoSearchTool

app.py

@@ -25,8 +25,9 @@ def get_web_search_results(query: str)-> str: #it's import to specify the return
     Args:
         query: A string representing a valid web query. IMPORTANT: Follow type str format strictly e.g. 'pictures of cats'.
     """
+    search_results_tool = DuckDuckGoSearchTool()
     try:
-        results = DuckDuckGoSearchTool(query)
+        results = search_results_tool(query)
         if results and results != "None":
             return results
         else: