مشکل در فلاتر

من موقع نصب یکی از پکیج های فلاتر به مشکل خوردم

دستور:
flutter pub add http

ارور
‍‍‍‍‍‍```
Because ** depends on flutterlints any which doesn't exist
(authorization failed), version solving failed.

Insufficient permissions to the resource at the https://pub.dev package repository.
You can modify credentials using:
dart pub token add https://pub.dev
Failed to update packages.