`avoid-accidental-submissions` should work when merging PRs #4461

1. Find PR you can merge, like https://github.com/sindresorhus/refined-github/pull/4395
2. Open merge box
3. Focus commit title field
4. Press [enter]

   <img width="811" alt="Screen Shot" src="https://user-images.githubusercontent.com/1402241/121675094-23139080-cadd-11eb-871d-b728cc782d4a.png">

The submissions should be avoided