fixed inference fn

app.py

@@ -92,7 +92,7 @@ def inference(text, n_timesteps):
         n_timesteps=n_timesteps,
         temperature=1.5,
         stoc=False,
-        spk=torch.LongTensor([0]) if len(SPEAKERS) > 1 else None,
+        spk=torch.LongTensor([0]) if SPEAKERS > 1 else None,
         length_scale=1.0,
     )