Use built-in apply_chat_template

[ahuang11]

I tried to design my own apply_template function, but I found that there's one from transformers.
https://github.com/holoviz-topics/panel-chat-examples/blob/main/docs/examples/mistral/mistral_with_memory.py

from transformers import AutoTokenizer

tokenizer = AutoTokenizer.from_pretrained("mistralai/Mistral-7B-v0.1")
chat = [
  {"role": "system", "content": "You are a helpful bot."},
  {"role": "user", "content": "Hello, how are you?"},
  {"role": "assistant", "content": "I'm doing great. How can I help you today?"},
  {"role": "user", "content": "I'd like to show off how chat templating works!"},
]

print(tokenizer.apply_chat_template(chat, tokenize=False))

[ahuang11]

Something about this isn't supported with ctransformers.

[ahuang11]

Working example in holoviz/panel#5764, but involves transformers lib too.