title: Command 'ui' is not defined in laravel 6.0
body: <p>I start a new project in laravel but my composer installed a fresh version of laravel 6.0.1. </p>
  
  <p><code>Php artisan make:auth</code> command can't work. </p>
  
  <p>I try many times but error can't remove</p>
  
  <pre><code>composer require laravel/ui
  </code></pre>
  
  <p>installed but
  when I use the second command: </p>
  
  <pre><code>php artisan ui vue --auth
  </code></pre>
  
  <p>then system show me this message:</p>
  
  <pre><code>Command "ui" is not defined.
  Using version ^1.0 for laravel/ui
  ./composer.json has been updated
  Loading composer repositories with package information
  Updating dependencies (including require-dev)
  PHP Fatal error:  Allowed memory size of 536870912 bytes exhausted (tried to allocate 4096 bytes) in phar://C:/ProgramData/ComposerSetup/bin/composer.phar/src/Composer/DependencyResolver/RuleSetGenerator.php on line 129
  
  Fatal error: Allowed memory size of 536870912 bytes exhausted (tried to allocate 4096 bytes) in phar://C:/ProgramData/ComposerSetup/bin/composer.phar/src/Composer/DependencyResolver/RuleSetGenerator.php on line 129
  
  Check https://getcomposer.org/doc/articles/troubleshooting.md#memory-limit-errors for more info on how to handle out of memory errors.
  </code></pre>