Update ui_extra_networks_checkpoints.py

Author: Artheriax

modules/ui_extra_networks_checkpoints.py

@@ -83,4 +83,4 @@ def list_items(self):
         return items
 
     def allowed_directories_for_previews(self):
-        return [v for v in [shared.opts.ckpt_dir, reference_dir, sd_models.model_path] if v is not None]
+        return [v for v in [shared.opts.ckpt_dir, reference_dir, sd_models.model_path] if v is not None]