Fix app.py removing list

app.py

@@ -12,7 +12,7 @@ def download_audio(audio_url, filename):
   
     # send a HTTP request to the server and save 
     # the HTTP response in a response object called r 
-    with open(["audio/" + filename],'wb') as f: 
+    with open("audio/" + filename,'wb') as f: 
   
         # Saving received content as a mp3 file in 
         # binary format