limit gradio queue to 1 concurrency and max 20 queued tasks

app.py

@@ -263,4 +263,4 @@ with gr.Blocks(css=css) as demo:
     woo.release(fn=predict, inputs=inputs, outputs=outputs, show_progress="minimal", show_api=False)
     smile.release(fn=predict, inputs=inputs, outputs=outputs, show_progress="minimal", show_api=False)
 
-demo.queue(api_open=False, max_concurrency=2).launch(share=False, show_error=True, show_api=False, ssr_mode=False)
+demo.queue(api_open=False, default_concurrency_limit=1, max_size=20).launch(share=False, show_error=True, show_api=False, ssr_mode=False)