title: How to override the validation rule login Laravel\Fortify?
body: <p>This described in the class Laravel\Fortify\Http\Requests\LoginRequest<br>
  I want to add one more validation line</p>
  <pre><code>namespace Laravel\Fortify\Http\Requests;
  
  use Illuminate\Foundation\Http\FormRequest;
  use Laravel\Fortify\Fortify;
  
  class LoginRequest extends FormRequest
  {
  /..
      public function rules()
          {
              return [
                  Fortify::username() =&gt; 'required|string',
                  'password' =&gt; 'required|string',
              ];
          }
  }
  </code></pre>
  <p>But I cannot do the customizations in the vendor.<br>
  My question is how to do this?</p>