Update dice.py (#220)

Author: anwai98

torch_em/loss/dice.py

@@ -89,6 +89,7 @@ def __init__(self, channelwise=True, eps=1e-7, reduce_channel="sum"):
         super().__init__()
         self.channelwise = channelwise
         self.eps = eps
+        self.reduce_channel = reduce_channel
 
         # all torch_em classes should store init kwargs to easily recreate the init call
         self.init_kwargs = {"channelwise": channelwise, "eps": self.eps, "reduce_channel": self.reduce_channel}