remove demo.m4a if exists

app.py

@@ -1,6 +1,7 @@
 import streamlit as st
 from pytube import YouTube
 import yt_dlp
+import os
 
 
 # from faster_whisper import WhisperModel
@@ -57,6 +58,8 @@ ydl_opts = {
 
 if st.session_state.youtube_url:
     with st.status("Get video Audio..."):
+        if os.path.exists('demo.m4a'):
+            os.remove('demo.m4a')
         with yt_dlp.YoutubeDL(ydl_opts) as ydl:
             error_code = ydl.download([st.session_state.youtube_url])