The main motivation for the upgrade is to use RuboCop 0.91+
(https://github.com/rubocop-hq/rubocop/blob/master/CHANGELOG.md#changes-14)
which fixes a caching bug
(https://github.com/rubocop-hq/rubocop/issues/8629) fixed by the
following pull request:
https://github.com/rubocop-hq/rubocop/pull/8633.
Signed-off-by: Rémy Coutable <remy@rymai.me>