Add default chat template to tokenizer_config.json

tokenizer_config.json

@@ -1 +1,4 @@
-{"model_max_length": 1024}
+{
+  "model_max_length": 1024,
+  "chat_template": "{% for message in messages %}{{'<|im_start|>' + message['role'] + '\n' + message['content'] + '<|im_end|>' + '\n'}}{% endfor %}{% if add_generation_prompt %}{{ '<|im_start|>assistant\n' }}{% endif %}"
+}