Adds grad-cam support on classifiers

src/ptbench/scripts/calculate_road.py

@@ -335,7 +335,7 @@ def calculate_road(
             )
         target_layers = [model.fc14]  # Last non-1x1 Conv2d layer
     else:
-        target_layers = [model.denseblock4.denselayer16.conv2]
+        target_layers = [model.model_ft.features.denseblock4.denselayer16.conv2]
 
     for vis_type in visualization_types:
         cam = create_cam(vis_type, model, target_layers, use_cuda)