[NFC] polish colossalai/nn/loss/loss_2p5d.py code style (#1553)

colossalai/nn/loss/loss_2p5d.py

@@ -30,6 +30,7 @@ class CrossEntropyLoss2p5D(_Loss):
     More details about ``args``, ``kwargs`` and ``torch.nn.functional.cross_entropy`` could be found in
     `Cross_entropy <https://pytorch.org/docs/stable/generated/torch.nn.functional.cross_entropy.html#torch.nn.functional.cross_entropy>`_.
     """
+
     def __init__(self, reduction=True, *args, **kwargs):
         super().__init__()
         assert_tesseract_initialization()
@@ -127,6 +128,7 @@ class VocabParallelCrossEntropyLoss2p5D(_Loss):
     Args:
         reduction (bool, optional): whether to average the loss, defaults to True.
     """
+
     def __init__(self, reduction=True):
         super().__init__()
         self.reduction_mean = reduction