add pin login and add pin code

lib/pages/staff/model/staff_model.dart

@@ -81,7 +81,7 @@ class StaffModel extends BaseModel {
   Future<void> updatePin(
       {required String userID,
       required bool enablePin,
-      required int? pin}) async {
+      required String? pin}) async {
     await request("/employee/pin", "PUT",
         payload: {"id": userID, "enable_pin_login": enablePin, "pin": pin},
         token: await getToken());