socialite

Use the public method to get the scopes

There may be a scenario when the class can be extended and override the scopes (or add additional ones for example in case of GoogleProvider), example:

```php
<?php
use Laravel\Socialite\Two\GoogleProvider;
class YoutubeProvider extends GoogleProvider {
    public function getScopes()
    {
        return array_merge(parent::getScopes(), [
            'https://www.googleapis.com/auth/youtube.readonly'
        ]);
    }
}
}```