Add `NoneDeletableModel` trait to package

[ultrono]

Ads a simple trait called NoneDeletableModel to the package. The trait could then be used in Eloquent models to deny all deletion attempts:

declare(strict_types=1);

namespace F9Web\LaravelDeletable\Traits\Traits;

use F9Web\LaravelDeletable\Traits\RestrictsDeletion;

trait NoneDeletableModel
{
    use RestrictsDeletion;

    public function isDeletable() : bool
    {
        return false;
    }
}

To prevent all deletion requests for a model:

declare(strict_types=1);

namespace App\Models;

use F9Web\LaravelDeletable\Traits\NoneDeletableModel;
use Illuminate\Database\Eloquent\Model;

class Order extends Model
{
   use NoneDeletableModel;
}

Now, orders cannot be deleted.