Don’t enforce %w[square brackets] for percent literals

[fanaugen]

As previously discussed here and there

Let’s treat each other like grown-ups: the difference between
%w(this style) and %w[that style] does not make or break readability,
but the cop does waste our time on every commit.

[zfhui]

I'm perfectly fine with this solution! ✅ Also see this issue.

[fanaugen]

merging this now;

these commits are kept intentionally small ("atomic") for easy revert in case anyone should miss the cop in question and want it back