Bump macOS version to 12
Bump macOS version to 12

With accordance to recommendations in
https://github.com/actions/runner-images/issues/5583

rakudo/rakudo,MasterDuke17/rakudo,salortiz/rakudo,labster/rakudo,rakudo/rakudo,tbrowder/rakudo,rakudo/rakudo,salortiz/rakudo,tbrowder/rakudo,rakudo/rakudo,labster/rakudo,salortiz/rakudo,MasterDuke17/rakudo,tbrowder/rakudo,tbrowder/rakudo,MasterDuke17/rakudo,MasterDuke17/rakudo,labster/rakudo,MasterDuke17/rakudo,rakudo/rakudo,salortiz/rakudo,salortiz/rakudo,MasterDuke17/rakudo,labster/rakudo,tbrowder/rakudo,rakudo/rakudo,tbrowder/rakudo,labster/rakudo,salortiz/rakudo,labster/rakudo