title: Update composer dependencies in json file on updating
body: <p>When I run <code>composer update</code>, a lot of dependencies and my composer.json get updated. But, my <code>composer.json</code> didn't change, so next time I run <code>composer install</code>, I'll get the outdated ones again.</p>
  
  <p>For instance, I have:</p>
  
  <pre><code>"require": {
          "symfony/form": "^4.1",
  }
  </code></pre>
  
  <p>When I run the command It shows:</p>
  
  <blockquote>
    <p>Updating symfony/dotenv (v4.1.4 => v4.1.5): Loading from cache</p>
  </blockquote>
  
  <p>But the json line stays the same, and <code>composer install</code> will install the <code>4.1.4</code> version.</p>
  
  <p>Is there a way to update the composer.json file when I run composer update?</p>
  
  <p>Thanks in advance!</p>