change rank function

src/backend/Components/User/UserManager.ts

         name: 'modifyPermissions' as 'modifyPermissions',
         exportRPCs: () => [
             this.getPermissions,
-            this.setPermission
+            this.setPermission,
+            this.changeRank
         ]
     },{
         name: 'softreserveCurrency' as 'softreserveCurrency',