Update tokenizer_config.json

Changed tokenizer_class to PreTrainedTokenizerFast

tokenizer_config.json

@@ -107,7 +107,7 @@
   "model_max_length": 1000000000000000019884624838656,
   "pad_token": "[PAD]",
   "sep_token": "[SEP]",
-  "tokenizer_class": "RobertaTokenizer",
+  "tokenizer_class": "PreTrainedTokenizerFast",
   "trim_offsets": true,
   "unk_token": "[UNK]"
 }