title: Delete Temp Files in Laravel Mix
body: <p>I'd like to remove temp build files during or after my laravel-mix build.<br>
  Here's some code that I have currently, but <code>del</code> isn't working:</p>
  
  <pre><code>const mix = require('laravel-mix');
  const del = require('del');
  
  // compile sass into temp css file
  mix.sass('resources/stylesheets/style.scss', 'public/css/temp.css');
  
  // compile css
  mix.styles([
      // other css stylesheets here...
      'public/css/temp.css' // include temp css file
  ], 'public/css/admin.min.css');
  
  // delete temp css file
  del('public/css/temp.css'); // not deleting the file
  </code></pre>