revert "constraints < 0.12" (#5124)
revert "constraints < 0.12" (#5124)

fpco/stackage,clinty/stackage,simonmichael/stackage,asr/stackage,soenkehahn/stackage,mrkkrp/stackage,iand675/stackage,Daniel-Diaz/stackage,michalkonecny/stackage,jonschoning/stackage,massysett/stackage