validate enums in PHP 8.0

I know that we can validate enums as seen in the documentation, but this is only available on PHP 8.1+ and I used PHP 8.0, for now, I won't use that.

I have the example below from this answer by @martinbean

class Post extends Model
{
    const STATUS_DRAFT = 1;
    const STATUS_PUBLISHED = 2;

    public function scopeDrafts($query)
    {
        return $query->whereStatus(static::STATUS_DRAFT);
    }

    public function scopePublished($query)
    {
        return $query->whereStatus(static::STATUS_PUBLISHED);
    }
}

How to validate those constants declared in Post model in a request? Something like the example below.

public function rules()
{
    return [
         'gender' => 'required|in:Male,Female',
    ];
}