Add 'servant-errors' package to Stackage
Add 'servant-errors' package to Stackage

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