title: I can not install Laravel 5.4 with composer
body: <p>I am trying to install <code>Laravel 5.4</code> with composer using composer. I get the following message. </p>
  
  <p>Here's a screenshot</p>
  
  <p><a href="https://i.stack.imgur.com/Ev9l7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Ev9l7.png" alt="enter image description here"></a></p>
  
  <p>What should I do?</p>