[minor] add type annotation for KernelRegion

Author: Zhijian Liu

torchsparse/utils/kernel_region.py

@@ -12,11 +12,10 @@
 
 class KernelRegion:
  def __init__(self,
- kernel_size=3,
- tensor_stride=1,
- dilation=1,
- dim=[0, 1, 2]):
-
+ kernel_size: int = 3,
+ tensor_stride: int = 1,
+ dilation: int = 1,
+ dim=[0, 1, 2]) -> None:
  self.kernel_size = kernel_size
  self.tensor_stride = tensor_stride
  self.dilation = dilation