Update app.py

app.py

@@ -131,7 +131,7 @@ def MixMelody(input_midi):
             
             patches = sorted(set([e[6] for e in c]))
             
-                if trg_patch in patches:
+            if trg_patch in patches:
                 
                 mixed_song.extend(mix_chord(c, src_harm_tones_chords[midx], trg_patch, src_melody_pitches[midx]))