92e370e6

Filter Haskell jobs for Nix CI (#155)

This applies the same filtering as I use for Garnix. It reduces the
number of jobs without excluding any derivations.
Time to Start Worker time Duration Time to finish
Config 0s 1s 1s 2s
Eval 3s 6s 6s 9s
Build 10s 1m11s 1m14s 1m24s
Suite 0s 1m19s 1m23s 1m24s