updated new flutter version

lib/widgets/general/payment_verification_code_dialog.dart

@@ -95,7 +95,7 @@ class PaymentVerificationCodeDialogState extends State<PaymentVerificationCodeDi
                           title: Text(S.of(context).error),
                           content: Text(S.of(context).wrong_payment_verification_code),
                           actions: [
-                            FlatButton(
+                            TextButton(
                               child: Text(S.of(context).ok),
                               onPressed: () {
                                 _pinPutController.clear();
@@ -124,7 +124,7 @@ class PaymentVerificationCodeDialogState extends State<PaymentVerificationCodeDi
         ],
       ),
       actions: [
-        FlatButton(
+        TextButton(
           child: Text(S.of(context).close),
           onPressed: () {
             Navigator.of(context).pop();