Added class validation for the enum

ref #6

src/models/enums/PermissionTargets.ts

@@ -4,5 +4,6 @@ export enum PermissionTarget {
     TEAM = 'RUNNERTEAM',
     TRACK = 'TRACK',
     USER = 'USER',
-    GROUP = 'USERGROUP'
+    GROUP = 'USERGROUP',
+    PERMISSION = 'PERMISSION'
 }