While the `minimum` and `maximum` methods have been available for a long
time for ActiveRecord relations, Rails 7.0 has added these methods for
enumerables as well.
This means that the `start_date` and `end_date` methods in the
ShiftsHelper can use `minimum` and `maximum` no matter whether they
receive an ActiveRecord relation or an array of polls (I think the
latter never happens, though, but I'm not 100% sure).