Fix EOS token

I think this will fix the issue below. I'm unsure whether `pad_token` also needs to be changed.

https://github.com/huggingface/swift-transformers/issues/98

tokenizer_config.json

@@ -118,7 +118,7 @@
   "bos_token": "<s>",
   "chat_template": "{{ bos_token }}{% for message in messages %}{% if (message['role'] == 'user') %}{{'<|user|>' + '\n' + message['content'] + '<|end|>' + '\n' + '<|assistant|>' + '\n'}}{% elif (message['role'] == 'assistant') %}{{message['content'] + '<|end|>' + '\n'}}{% endif %}{% endfor %}",
   "clean_up_tokenization_spaces": false,
-  "eos_token": "<|endoftext|>",
+  "eos_token": "<|end|>",
   "legacy": false,
   "model_max_length": 4096,
   "pad_token": "<|endoftext|>",