Fix the orphan endpoint
    
    In the previous commit we prevented anyone from orphaning packages
    but we prevented admins from doing it, which isn't what we meant to
    do, admins should be allowed to orphan any packages since sometime
    people become non-responsive.
    This commit fixes this, we now only allow the current main admin or
    admins to orphan packages.
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>