Fixing DistilBert error message (#20945)

Fixing error message

src/transformers/models/distilbert/tokenization_distilbert.py

@@ -166,7 +166,7 @@ class DistilBertTokenizer(PreTrainedTokenizer):
         if not os.path.isfile(vocab_file):
             raise ValueError(
                 f"Can't find a vocabulary file at path '{vocab_file}'. To load the vocabulary from a Google pretrained"
-                " model use `tokenizer = BertTokenizer.from_pretrained(PRETRAINED_MODEL_NAME)`"
+                " model use `tokenizer = DistilBertTokenizer.from_pretrained(PRETRAINED_MODEL_NAME)`"
             )
         self.vocab = load_vocab(vocab_file)
         self.ids_to_tokens = collections.OrderedDict([(ids, tok) for tok, ids in self.vocab.items()])