fix `brew cask` on darwin
fix `brew cask` on darwin

stuertz/restic,jayme-github/restic,ar-jan/restic,ar-jan/restic,restic/restic,episource/restic,stuertz/restic,pombredanne/restic,middelink/restic,middelink/restic,bchapuis/restic,byo/restic,byo/restic,fawick/restic,restic/restic,mappu/restic,jayme-github/restic,fawick/restic,kurin/restic,ckemper67/restic,arithmetric/restic,kurin/restic,howeyc/restic