delete auto mode

app.py

@@ -222,8 +222,8 @@ class DebateUI(WebUI):
                         label="Please input valid openai key for gpt-3.5-turbo-16k."
                     )
                     self.radio_mode = gr.Radio(
-                        [Client.SINGLE_MODE],
-                        value=Client.SINGLE_MODE,
+                        [Client.AUTO_MODE, Client.SINGLE_MODE],
+                        value=Client.AUTO_MODE,
                         interactive=True,
                         label = Client.MODE_LABEL,
                         info = Client.MODE_INFO