Fix CenterCrop transform

Author: datumbox

torchvision/prototype/transforms/_geometry.py

@@ -67,7 +67,7 @@ def _transform(self, inpt: Any, params: Dict[str, Any]) -> Any:
 
 
 class CenterCrop(Transform):
-    def __init__(self, size: List[int]):
+    def __init__(self, size: Union[int, Sequence[int]]):
         super().__init__()
         self.size = size