Add chat template in tokenizer_config.json

Add chat template in tokenizer_config.json so that we can use `tokenizer.apply_chat_template` for prompt templating

tokenizer_config.json

@@ -50,4 +50,5 @@
   "sp_model_kwargs": {},
   "tokenizer_class": "SEABPETokenizer",
   "unk_token": "<unk>"
+  "chat_template": "{% for message in messages %}{% if (message['role'] == 'user') != (loop.index0 % 2 == 0) %}{{ raise_exception('Conversation roles must alternate user/assistant/user/assistant/...') }}{% endif %}{% if message['role'] == 'user' %}### USER:\n{{ message['content'] + '\n\n' }}{% elif message['role'] == 'assistant' %}### RESPONSE:\n{{ message['content'] + '\n\n' }}{% else %}{{ raise_exception('Only user and assistant roles are supported!') }}{% endif %}{% endfor %}"
 }