Update concurrency.

app.py

@@ -137,4 +137,4 @@ with gr.Blocks(css=css) as demo:
     )
 
 
-demo.queue(default_concurrency_limit=1, max_size=5, api_open=False).launch(max_threads=256, show_api=False)
+demo.queue(default_concurrency_limit=4, max_size=5, api_open=False).launch(max_threads=256, show_api=False)