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());

lib/pages/staff/staff_pin_editor.dart

@@ -310,7 +310,7 @@ class _StaffPinEditorState extends State<StaffPinEditor> {
       await context.read<StaffModel>().updatePin(
           userID: _staff.id!,
           enablePin: _enablePinLogin,
-          pin: _enablePinLogin ? int.parse(_confirmPin) : null);
+          pin: _enablePinLogin ? _confirmPin : null);
       Navigator.pop(context, true);
     } catch (e) {
       showMsgDialog(context, "Error", e.toString());