stricter bounds that quickcheck-instances < 0.4, as 0.3.15 breaks the build

[shapr]

I tried to build this with cabal new-build, quickcheck-instances 0.3.15 has too low a bound for hashed, means the code can't import Hashed
I solved this by using quickcheck-instances 0.3.18
I did not test with 0.3.16 or 0.3.17