Update tokenizer class in tokenizer_config,json to llama tokenizer.

tokenizer_config.json

@@ -3,5 +3,5 @@
     "bos_token": "<s>",
     "eos_token": "</s>",
     "add_prefix_space": false,
-    "tokenizer_class": "PreTrainedTokenizerFast"
+    "tokenizer_class": "LlamaTokenizer"
 }