feat: Refactor clear_output function in app.py

The clear_output function in app.py has been refactored to simplify the code and improve readability. Instead of directly modifying the image_slider list, the function now returns a new list with None values for both elements. This change ensures consistency and reduces the chances of introducing bugs in the future.

app.py

@@ -271,9 +271,7 @@ with gr.Blocks(css=css) as demo:
 
     with gr.Row():
         def clear_output(image_slider):
-            image_slider[0] = None
-            image_slider[1] = None
-            return image_slider
+            return [None, None]
 
         with gr.Column():
             generated_image = gr.Image(label="Input Image", type="filepath")