Separate tidying

PR을 보낼 때 타이딩 PR과 기능을 수정하는 PR을 분리하기. 또는 아예 타이딩에 대해서는 PR을 따로 만들지 않기.

Once you get comfortable with tidying, with working in small steps, with working with absolute safety, I encourage you to experiment with not requiring reviews for tidying PRs. This reduces latency further, incentivizing even smaller tidying PRs. —Tidy first? A personal exercise in empirical software design