fix: factory {has,for}* methods should return static

[calebdw]

Hello!

The dynamic factory methods {has,for}* (e.g., ->hasUser()) should return static. This especially matters when you are inside the factory itself and are trying to call the methods inside a state:

class CommentFactory extends Factory
{
    public function foo(): static
    {
        return $this
             // this caused the whole chain to return CommentFactory instead of static(CommentFactory)!
            ->forUser()
            ->state(['foo' => 'bar']);
    }
}

This has been released on my fork if anyone would like to take advantage of this immediately.

Thanks!