Fix typo making dev run instead of 5.12

server.js

@@ -253,7 +253,7 @@ scheduleJob({hour: 0, minute: 0}, () => {
 });
 scheduleJob({hour: 22, minute: 0}, () => {
     console.log('Running health check for 5.12');
-    healthCheck({ref: '5.12'});
+    healthCheck({rev: '5.12'});
 });
 scheduleJob({hour: 23, minute: 0, dayOfWeek: 6}, () => {
     console.log('Running health check for 5.11');