title: Laravel fill with enum attribute gives error
body: <p>I have an Enum like:</p>
  <pre><code>&lt;?php
  
  namespace App\Models\helpers\Enums;
  
  enum ComissionamentoVendedor: string
  {
      case Faturamento = 'No faturamento';
      case Pagamento = 'Após o pagamento pelo cliente';
  }
  </code></pre>
  <p>And I have a model that uses this Enum</p>
  <pre><code>...
      public $casts = [
          'comissionamento_momento' =&gt; ComissionamentoVendedor::class,
      ];
  ...
  </code></pre>
  <p>But when I try to save it I get an error:</p>
  <pre><code>$vendedor = new Vendedor;
  $vendedor-&gt;fill($atributos);
  $vendedor-&gt;save();
  </code></pre>
  <p>The error is <code>ErrorException: Attempt to read property &quot;value&quot; on string</code></p>
  <p>It happens on the file <code>vendor/illuminate/database/Eloquent/Concerns/HasAttributes.php:951</code></p>
  <pre><code> protected function setEnumCastableAttribute($key, $value)
   {
       // $value here is a string, a valid value from ComissionamentoVendedor Enum, sent by the frontend but looks like Laravel expects to be an Enum
       $this-&gt;attributes[$key] = isset($value) ? $value-&gt;value : null;
   }
  </code></pre>
  <p>Am I doing something wrong? I'm actually using Lumen 8.3.3.</p>