I get Driver [slack] not supported when I run a backup

[i7strelok]

My config/backup.php:

    'notifications' => [

        'notifications' => [
            \Spatie\Backup\Notifications\Notifications\BackupHasFailedNotification::class => ['slack'],
            \Spatie\Backup\Notifications\Notifications\UnhealthyBackupWasFoundNotification::class => ['slack'],
            \Spatie\Backup\Notifications\Notifications\CleanupHasFailedNotification::class => ['slack'],
            \Spatie\Backup\Notifications\Notifications\BackupWasSuccessfulNotification::class => ['slack'],
            \Spatie\Backup\Notifications\Notifications\HealthyBackupWasFoundNotification::class => ['slack'],
            \Spatie\Backup\Notifications\Notifications\CleanupWasSuccessfulNotification::class => ['slack'],
        ],

        /*
         * Here you can specify the notifiable to which the notifications should be sent. The default
         * notifiable will use the variables specified in this config file.
         */
        'notifiable' => \Spatie\Backup\Notifications\Notifiable::class,

        'mail' => [
            'to' => 'my@mail.com',

            'from' => [
                'address' => env('MAIL_FROM_ADDRESS', 'hello@example.com'),
                'name' => env('MAIL_FROM_NAME', 'Example'),
            ],
        ],

        'slack' => [
            'webhook_url' => env('LOG_SLACK_WEBHOOK_URL'),

            /*
             * If this is set to null the default channel of the webhook will be used.
             */
            'channel' => null,

            'username' => null,

            'icon' => null,

        ],

When I run a backup:

[2023-07-28 09:50:42] local.ERROR: Driver [slack] not supported. {"exception":"[object] (InvalidArgumentException(code: 0): Driver [slack] not supported. at /Users/admin/Homestead/sites/mysite/vendor/laravel/framework/src/Illuminate/Support/Manager.php:109)
[stacktrace]

Why?

[parallels999]

https://spatie.be/docs/laravel-backup/v8/installation-and-setup