Fix tokenizer_config.json EOS token (#3)

- Use `<|im_end|>` as EOS token in `tokenizer_config.json` (9e2f067c57c073064f34f85df854b712ffd0ba5a)

tokenizer_config.json

@@ -2,7 +2,7 @@
   "add_prefix_space": false,
   "bos_token": "<|endoftext|>",
   "clean_up_tokenization_spaces": true,
-  "eos_token": "<|endoftext|>",
+  "eos_token": "<|im_end|>",
   "model_max_length": 1000000000000000019884624838656,
   "tokenizer_class": "GPTNeoXTokenizer",
   "unk_token": "<|endoftext|>"