fix AudioSignal \audio concatenation (probably still wrong)

app.py

@@ -80,7 +80,7 @@ def process_fn(input_audio_path, seed, guidance_scale, num_inference_steps):
             audio_concat = audio
             #audio_concat = audio[0]
         else:
-            audio_concat = scipy.concatenate((audio_concat, audio))
+            audio_concat += audio
 
     scipy.io.wavfile.write(outfile, rate=48000, data=audio_concat)
     return outfile