Add missing regex to validate serial
Add missing regex to validate serial

dennypage/pfsense,NewEraCracker/pfsense,dennypage/pfsense,phil-davis/pfsense,pfsense/pfsense,phil-davis/pfsense,pfsense/pfsense,pfsense/pfsense,NewEraCracker/pfsense,pfsense/pfsense,phil-davis/pfsense,phil-davis/pfsense,NewEraCracker/pfsense,dennypage/pfsense,dennypage/pfsense,NewEraCracker/pfsense