use different version of gradio as the current one has many bugs

app.py

@@ -6,7 +6,10 @@ import numpy as np
 import torch
 
 from InferenceInterfaces.Meta_FastSpeech2 import Meta_FastSpeech2
+import os
 
+os.system("pip uninstall -y gradio")
+os.system("pip install gradio==2.7.5")
 
 def float2pcm(sig, dtype='int16'):
     """