[5.4] fix eloquent collection contains issue

[storyn26383]

I think this pull request can fix below issue:

$post = Post::create(['id' => 1]);
$comment = Comment::create(['id' => 1]);

$collection = new EloquentCollection([$post]);

$collection->contains($comment); // expect is false, but true given

[ntzm]

Can we use $model->is($key) instead if possible? That has some additional checks such as connection as well!

[storyn26383]

Thanks for advice, much better now 😜