Fix regression on Processor.save_pretrained caused by #31691 (#32921)

fix save_pretrained

src/transformers/processing_utils.py

@@ -522,7 +522,7 @@ def save_pretrained(self, save_directory, push_to_hub: bool = False, **kwargs):
                 token=kwargs.get("token"),
             )
 
-        if set(self.to_dict().keys()) == {"processor_class"}:
+        if set(processor_dict.keys()) == {"processor_class"}:
             return []
         return [output_processor_file]