Fix error message in `WhisperFeatureExtractor` (#20936)

* Fix error message

* Fix code quality

src/transformers/models/whisper/feature_extraction_whisper.py

@@ -271,9 +271,9 @@ class WhisperFeatureExtractor(SequenceFeatureExtractor):
         if sampling_rate is not None:
             if sampling_rate != self.sampling_rate:
                 raise ValueError(
-                    f"The model corresponding to this feature extractor: {self} was trained using a sampling rate of"
-                    f" {self.sampling_rate}. Please make sure that the provided `raw_speech` input was sampled with"
-                    f" {self.sampling_rate} and not {sampling_rate}."
+                    f"The model corresponding to this feature extractor: {self.__class__.__name__} was trained using a"
+                    f" sampling rate of {self.sampling_rate}. Please make sure that the provided `raw_speech` input"
+                    f" was sampled with {self.sampling_rate} and not {sampling_rate}."
                 )
         else:
             logger.warning(