[engine.saliency.viewer] Fix use of heatmap from matplotlib

src/ptbench/engine/saliency/viewer.py

@@ -102,7 +102,7 @@ def _overlay_saliency_map(
     result = numpy.where(
         saliencies[..., numpy.newaxis] == 0,
         image_array,
-        (image_weight * image_array) + ((1 - image_weight) * heatmap),
+        (image_weight * image_array) + ((1 - image_weight) * heatmap[:, :, :3]),
     )
 
     return PIL.Image.fromarray((result * 255).astype(numpy.uint8), "RGB")