fix(args): determine if the only arguments allowed are also required
fix(args): determine if the only arguments allowed are also required

clap-rs/clap,nelsonjchen/clap-rs,nelsonjchen/clap-rs,grossws/clap-rs,grossws/clap-rs,darayus/clap-rs,darayus/clap-rs,wezm/clap-rs,sru/clap-rs,Vinatorul/clap-rs,sru/clap-rs,cstorey/clap-rs,wezm/clap-rs,kbknapp/clap-rs,grossws/clap-rs,sru/clap-rs,cstorey/clap-rs,clap-rs/clap,kbknapp/clap-rs,clap-rs/clap,Vinatorul/clap-rs,daboross/clap-rs,daboross/clap-rs,daboross/clap-rs,nelsonjchen/clap-rs,darayus/clap-rs,wezm/clap-rs,Vinatorul/clap-rs,cstorey/clap-rs