Fix deprecation warning: Replace deprecated median_filter import

Signed-off-by: Arunabh <[email protected]>

Author: Foxglove144

art/defences/preprocessor/spatial_smoothing.py

@@ -30,7 +30,7 @@
 from typing import Optional, Tuple
 
 import numpy as np
-from scipy.ndimage.filters import median_filter
+from scipy.ndimage import median_filter
 
 from art.utils import CLIP_VALUES_TYPE
 from art.defences.preprocessor.preprocessor import Preprocessor