Remove unused imports that are later redefined

Reviewed By: jreese, ppwwyyxx

Differential Revision: D32191010

fbshipit-source-id: 1e40b7a090be3a0e25b930fb908ec177719fce50

d2go/data/transforms/crop.py

@@ -8,7 +8,7 @@ from typing import List, Optional, Tuple, Union, Any
 import detectron2.data.transforms.augmentation as aug
 import numpy as np
 from detectron2.config import CfgNode
-from detectron2.data.transforms import ExtentTransform, CropTransform
+from detectron2.data.transforms import ExtentTransform
 from detectron2.structures import BoxMode
 
 from . import box_utils as bu