fix typo

app.py

@@ -262,7 +262,7 @@ with gr.Blocks() as demo:
                             preprocess=preprocess_example,
                             fn=func,
                             cache_examples=True)
-        with gr.Columns():
+        with gr.Column():
             gr.Markdown(value='### Model prediction legend')
             gr.Image(value='Legend.png', image_mode='RGB', show_label=False)