style: format conversion_mapping.py with ruff

Author: zozo123

src/transformers/conversion_mapping.py

@@ -623,9 +623,7 @@ def get_model_conversion_mapping(
 
     # Recurse over submodules and collect all conversions
     inner_model = getattr(model, "model", None)
-    nested_language_model = (
-        getattr(inner_model, "language_model", None) if inner_model is not None else None
-    )
+    nested_language_model = getattr(inner_model, "language_model", None) if inner_model is not None else None
     for submodule in model.modules():
         if (
             submodule is not model