minor change

[kojix2]

Hi

This is a completely unimportant pull request.
Make test_num_tokens_from_messages look the same as test_get_chat_completion_max_tokens.

I am working on a Crystal binding for this library; this is my second day studying Rust and this is my first Rust pull request.

Feel free to close this one as it does not contain any essential changes. Thanks.

tiktoken-rs/tiktoken-rs/src/api.rs

Lines 440 to 447 in 9decafb

	let model = "gpt-3.5-turbo";
	let messages = &[async_openai::types::ChatCompletionRequestMessage {
	content: Some("You are a helpful assistant that only speaks French.".to_string()),
	role: async_openai::types::Role::System,
	name: None,
	function_call: None,
	}];
	let max_tokens = get_chat_completion_max_tokens(model, messages).unwrap();

[zurawiki]

Thanks for the PR. Happy to make the test code more consistent