Update tokenizer_config.json

for https://github.com/oobabooga/text-generation-webui

tokenizer_config.json

@@ -23,6 +23,6 @@
   "eos_token": "<|endoftext|>",
   "model_max_length": 1000000000000000019884624838656,
   "pad_token": "<|padding|>",
-  "tokenizer_class": "GPTNeoXTokenizer",
+  "tokenizer_class": "GPTNeoXTokenizerFast",
   "unk_token": "<|endoftext|>"
 }