Remove FeatherNotes package
As part of https://git.pantherx.org/development/guix-pantherx/-/issues/276 FeatherNotes is already in our base repo, so there's no need to have it here.
As part of https://git.pantherx.org/development/guix-pantherx/-/issues/276 FeatherNotes is already in our base repo, so there's no need to have it here.