Revert "Workaround for `bundle conflict` in AppVeyor"
Revert "Workaround for `bundle conflict` in AppVeyor"

This reverts commit ae8a37dd19a0f9d74baf697c2564c7455de25436.

appveyor/ci#1944 has been resolved. This PR will revert the workaround.

petehamilton/rubocop,sue445/rubocop,rrosenblum/rubocop,vergenzt/rubocop,tdeo/rubocop,deivid-rodriguez/rubocop,pocke/rubocop,pocke/rubocop,bbatsov/rubocop,haziqhafizuddin/rubocop,panthomakos/rubocop,jmks/rubocop,vergenzt/rubocop,panthomakos/rubocop,rrosenblum/rubocop,petehamilton/rubocop,tdeo/rubocop,bquorning/rubocop,vergenzt/rubocop,sue445/rubocop,jfelchner/rubocop,maxjacobson/rubocop,deivid-rodriguez/rubocop,smakagon/rubocop,scottmatthewman/rubocop,meganemura/rubocop,smakagon/rubocop,tejasbubane/rubocop,deivid-rodriguez/rubocop,jmks/rubocop,meganemura/rubocop,palkan/rubocop,palkan/rubocop,mikegee/rubocop,panthomakos/rubocop,bquorning/rubocop,scottmatthewman/rubocop,tejasbubane/rubocop,urbanautomaton/rubocop,palkan/rubocop,akihiro17/rubocop,tdeo/rubocop,jfelchner/rubocop,haziqhafizuddin/rubocop,mikegee/rubocop,petehamilton/rubocop,mikegee/rubocop,rrosenblum/rubocop,jfelchner/rubocop,maxjacobson/rubocop,maxjacobson/rubocop,bquorning/rubocop,urbanautomaton/rubocop,jmks/rubocop,akihiro17/rubocop,meganemura/rubocop,bbatsov/rubocop,akihiro17/rubocop,sue445/rubocop,tejasbubane/rubocop