This gem locks the rubocop dependency to ~> 0.78.0, which prevents using more recent releases of Rubocop (current is 0.82.0, and there are a bunch of fixes in head about to be released as well).
The bug fix list between 0.78.0 and 0.82.0 is quite huge:
https://github.com/rubocop-hq/rubocop/blob/master/CHANGELOG.md
Is there a reason the dependency lock is so strict here?