update the chat_template as VLLM suggested (#2)

- update the chat_template as VLLM suggested (5f702cd18e6960a50b9a4acf975a39bff118bbb7)

chat_template.json

@@ -1,3 +1,3 @@
 {
-  "chat_template": "{% for message in messages %}{% if loop.index0 == 0 %}{{bos_token}}{% endif %}{{'<|start_header_id|>' + message['role'] + '<|end_header_id|>\n\n' }}{% for content in message['content'] %}{% if content['type'] == 'image' %}{{ '<|image|>' }}{% elif content['type'] == 'text' %}{{ content['text'] }}{% endif %}{% endfor %}{{ '<|eot_id|>' }}{% endfor %}{% if add_generation_prompt %}{{ '<|start_header_id|>assistant<|end_header_id|>\n\n' }}{% endif %}"
+  "chat_template": "{% for message in messages %} {% if loop.index0 == 0 %} {{ bos_token }} {% endif %} {{ '<|start_header_id|>' + message['role'] + '<|end_header_id|>\n\n' }} {% if message['content'] is string %} {{ message['content'] }} {% else %} {% for content in message['content'] %} {% if content['type'] == 'image' %} {{ '<|image|>' }} {% elif content['type'] == 'text' %} {{ content['text'] }} {% endif %} {% endfor %} {% endif %} {{ '<|eot_id|>' }} {% endfor %} {% if add_generation_prompt %} {{ '<|start_header_id|>assistant<|end_header_id|>\n\n' }} {% endif %}"
 }