title: transform on a laravel collection is not changing an attribute
body: <p>In the following code, the &quot;liked_by_me&quot; column remains unchanged but the &quot;newAttr&quot; column is added.</p>
  <pre><code>    $commentList-&gt;transform(function($item, $key) {
          $item-&gt;liked_by_me == null ? $item-&gt;liked_by_me = false : $item-&gt;liked_by_me = true;
          $item-&gt;liked_by_me == null ? $item-&gt;newAttr = false : $item-&gt;newAttr = true;
          return $item;
      });
  </code></pre>
  <p>The $commentList collection is the result of a read from the DB using a standard model for the comments table.  I am running Laravel 8</p>
  <p>There seems to be no way to change an existing attribute in the rows of the resulting collection, but adding new attributes works.  I have also tried various iterations using -&gt;map() and -&gt;each and nothing seems to allow me to alter an attribute of a row in a collection retrieved from the DB.</p>