change async to non_blocking

The async keyword is a reserved keyword in Python 3.7 Fix #24 (closed)

bob/learn/pytorch/preprocessor/audio/DltResNet.py

@@ -148,7 +148,7 @@ class DltResNetExtractor(Preprocessor):
           with torch.no_grad():
             in_batch = numpy.array(batch)
             if cuda_flag == 1:
-                input_var = torch.autograd.Variable(torch.Tensor(in_batch).unsqueeze(1).cuda(async=True))
+                input_var = torch.autograd.Variable(torch.Tensor(in_batch).unsqueeze(1).cuda(non_blocking=True))
             else:
                 input_var = torch.autograd.Variable(torch.Tensor(in_batch).unsqueeze(1))
             fX = model(input_var).data.cpu().numpy()