Remove Tensorflow Python internal reference

Author: Licht-T

tensorflow_addons/layers/deformable_conv2d.py

@@ -19,7 +19,7 @@
 from typeguard import typechecked
 from tensorflow_addons.utils import types
 from tensorflow_addons.utils.resource_loader import LazySO
-from tensorflow.python.keras.utils import conv_utils
+from tensorflow.keras.utils import conv_utils
 
 _deformable_conv2d_ops_so = LazySO("custom_ops/layers/_deformable_conv2d_ops.so")