8dcf6e0a

Author: Greg Pfeil <greg@technomadic.org>

Committer: GitHub <noreply@github.com>

Cancel old Haskell build matrices (#197)

Haskell projects create a large build matrix, and when new changes are
pushed, we want to cancel the previous to minimize wasting CI resources
(in March, GitHub actually cut me off, so I’m using _way_ too much CI
time).