CODEOWNERS: update for slipdev and sliptty
CODEOWNERS: update for slipdev and sliptty

OlegHahm/RIOT,yogo1212/RIOT,kYc0o/RIOT,yogo1212/RIOT,OlegHahm/RIOT,jasonatran/RIOT,kaspar030/RIOT,basilfx/RIOT,OTAkeys/RIOT,ant9000/RIOT,yogo1212/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,RIOT-OS/RIOT,kaspar030/RIOT,authmillenon/RIOT,yogo1212/RIOT,jasonatran/RIOT,yogo1212/RIOT,jasonatran/RIOT,kYc0o/RIOT,authmillenon/RIOT,authmillenon/RIOT,ant9000/RIOT,ant9000/RIOT,smlng/RIOT,RIOT-OS/RIOT,ant9000/RIOT,basilfx/RIOT,smlng/RIOT,kaspar030/RIOT,OlegHahm/RIOT,OlegHahm/RIOT,OTAkeys/RIOT,yogo1212/RIOT,kaspar030/RIOT,miri64/RIOT,miri64/RIOT,RIOT-OS/RIOT,authmillenon/RIOT,jasonatran/RIOT,smlng/RIOT,basilfx/RIOT,authmillenon/RIOT,miri64/RIOT,miri64/RIOT,smlng/RIOT,smlng/RIOT,jasonatran/RIOT,miri64/RIOT,OTAkeys/RIOT,kYc0o/RIOT,kYc0o/RIOT,kYc0o/RIOT,basilfx/RIOT,kaspar030/RIOT,RIOT-OS/RIOT,OlegHahm/RIOT,ant9000/RIOT,OTAkeys/RIOT,OTAkeys/RIOT,basilfx/RIOT