`show-whitespace` should not run on diff/patch headers #4843

Not really a bug, but it's not useful here

<img width="659" alt="Screen Shot 10" src="https://user-images.githubusercontent.com/1402241/135712951-d8e6a1ec-f333-451d-8e90-21b0345ec846.png">

Example URL

https://github.com/sindresorhus/refined-github/commit/e8ec186217ffc42f351983b22187ee14efb9251b#diff-6a8348ff857b16e455a52ddd651b49f31cd05895459c37301051a0e30bcf077c

Browser(s) used

safari