fix the warning when training (#673)

change ByteTensor to BoolTensor

Author: TQuy

beginner_source/chatbot_tutorial.py

@@ -537,7 +537,7 @@ def outputVar(l, voc):
     max_target_len = max([len(indexes) for indexes in indexes_batch])
     padList = zeroPadding(indexes_batch)
     mask = binaryMatrix(padList)
-    mask = torch.ByteTensor(mask)
+    mask = torch.BoolTensor(mask)
     padVar = torch.LongTensor(padList)
     return padVar, mask, max_target_len