cda4538b 

Add `cabal check` to Haskell flake

Get some assurance that Hackage will accept a published package.
Time to Start Worker time Duration Time to finish
Config 0s 1s 1s 1s
Eval 1s 4s 4s 5s
Build 6s 3m34s 3m36s 3m42s
Suite 0s 3m39s 3m42s 3m42s