Add bos and eos token to tokenizer config.

tokenizer_config.json

@@ -33,7 +33,9 @@
       "special": true
     }
   },
+  "bos_token": "<|begin_of_text|>",
   "clean_up_tokenization_spaces": true,
+  "eos_token": "<|end_of_text|>",
   "model_max_length": 1000000000000000019884624838656,
   "tokenizer_class": "PreTrainedTokenizerFast"
 }