Update app.py

Removed image as output since undefined type

app.py

@@ -51,7 +51,7 @@ def get_current_time_in_timezone(timezone: str) -> str:
         return f"Error fetching time for timezone '{timezone}': {str(e)}"
 
 @tool
-def generate_image(description: str) -> image:
+def generate_image(description: str):
     """A tool that generates an image from a text description.
     Args:
         description: A string representing the text description to generate an image of.