Laravel `PersistProcessor` always throwing error on `HasMany` and `MorphMany` relationships.

[jonerickson]

API Platform version(s) affected: 4.1.15

Description
The Laravel persist processor checks the HasMany and MorphMany relationships on L62 of ApiPlatform\Laravel\Eloquent\State\PersistProcessor. A RuntimeException is thrown if the relation is not an array. These relationships return a Collection, not an array, thus always throwing an error.

if (HasMany::class === $relation['type'] || MorphMany::class === $relation['type']) {
    $rel = $data->{$relation['name']};

    if (!\is_array($rel)) {
        throw new RuntimeException('To-Many relationship is not a collection.');
    }

    $toMany[$relation['method_name']] = $rel;
    unset($data->{$relation['name']});
    $this->relations[$relation['method_name']] = $relation['name'];
}

How to reproduce
Create a model as an ApiResource. Add a MorphMany relationship and try to create a new instance via a standard POST request.

Possible Solution
L66 should be changed to:

if (!\is_array($rel) && !\is_a($rel, Collection::class)) {
    throw new RuntimeException('To-Many relationship is not a collection.');
}