Skip the check for WIP commits

[mathstuf]

If a commit message subject starts with WIP (also seen as [WIP] and lowercase), allowing otherwise blocked content without a prompt would be useful.

[sktguha]

agreed. it is a good feature. following

[pimterry]

I'd definitely accept PRs for this.

I'd prefer the prefix to be a configurable regex (like the confirm matches themselves), rather than hardcoding a list myself, but I'd be fine with WIP\b as a default.