PITTSBURGH — The Cardinals scored their first six runs of the game on a pair of home runs, including a grand slam from recently struggling slugger Nolan Gorman, and held off a push from the Pittsburgh Pirates to start their road trip with a win. Alec Burleson and Gorman bashed home runs to give the Cardinals a six-run lead after four innings, and they withstood a fifth-inning rally to secure a 7…