change page navigation

lib/pages/rates/shipment_rates_calculate.dart

@@ -2,6 +2,7 @@ import 'package:fcs/helpers/theme.dart';
 import 'package:fcs/localization/app_translations.dart';
 import 'package:fcs/pages/rates/model/shipment_rate_model.dart';
 import 'package:fcs/pages/widgets/progress.dart';
+import 'package:flutter/cupertino.dart';
 import 'package:provider/provider.dart';
 
 import 'package:flutter/material.dart';
@@ -37,9 +38,7 @@ class _ShipmentRatesCalState extends State<ShipmentRatesCal> {
         appBar: AppBar(
           centerTitle: true,
           leading: new IconButton(
-            icon: new Icon(
-              Icons.close,
-            ),
+            icon: new Icon(CupertinoIcons.back),
             onPressed: () => Navigator.of(context).pop(),
           ),
           backgroundColor: primaryColor,