Update tokenizer class for Transformers v4 compatibility (#2)

- Update tokenizer class for Transformers v4 compatibility (e4f8896b16148f4f66a305b2f0512603d23cc1ed)


Co-authored-by: Kiho Kim <kyoui-dev@users.noreply.huggingface.co>

tokenizer_config.json

@@ -10,7 +10,7 @@
   "model_max_length": 1000000000000000019884624838656,
   "pad_token": "<pad>",
   "processor_class": "PixtralProcessor",
-  "tokenizer_class": "TokenizersBackend",
+  "tokenizer_class": "LlamaTokenizerFast",
   "unk_token": "<unk>",
   "use_default_system_prompt": false
 }