Fix for readonly properties that declared in parent

[MrMeshok]

If you try to serialize an object that has readonly properties that declared in parent, you will get an error "Cannot initialize readonly property Parent::$property from scope Child". This PR fixes this

class Parent
{
    public function __construct(
        public readonly int $property = 1,
    ) {}
}

class Child extends Parent {}

$object = new Child();

$closure = static fn () => $object;

serialize(new \Laravel\SerializableClosure\SerializableClosure($closure));

[taylorotwell]

Drafting pending review from @nunomaduro

[nunomaduro]

I've tested it locally, and seems to be working.