[macos] Install `GPG`
[macos] Install `GPG`

Ref https://www.gnupg.org/
Fix alrra/dotfiles#32

girishramnani/dotfiles,makabde/dotfiles,makabde/dotfiles,christophermoura/dotfiles,christophermoura/dotfiles,mickael83/ubuntu-dotfiles,AlbertoElias/dotfiles,girishramnani/dotfiles,oddlord/dotfiles,AlbertoElias/dotfiles,pbrooks/dotfiles,b-boogaard/dotfiles,mickael83/ubuntu-dotfiles