title: How to validate multipart file on AdonisJS?
body: <p>I am using <code>Adonis.js</code> in the latest version but cannot validate...
  Already tried</p>
  
  <pre><code>request.multipart.file('avatar', {
    types: ['jpeg', 'jpg', 'png'], // I already tried -&gt; type: ['image'] types: ['image'],
    size: "4mb"
    }, async file =&gt; {
      await Drive.put(key, file.stream)
  })
  </code></pre>
  
  <p><code>.../Validators/changeAvatar.js</code></p>
  
  <pre><code>'use strict'
  
  class UserChangeAvatar {
    get rules() {
      return {
        avatar: 'required|file|file_ext:png,jpg,jpeg,svg'
      }
    }
  }
  
  module.exports = UserChangeAvatar
  </code></pre>
  
  <p>Nothing works, the code lets you upload any type of file, like <code>.pdf</code> or <code>.mp4</code></p>
  
  <p>There's nothing in the Adonis.js documentation talking about it either.</p>
  
  <h3>Package version</h3>
  
  <p>Version 4.1
  <code>"@adonisjs/framework": "^5.0.9"</code></p>
  
  <h3>Node.js and npm version</h3>
  
  <p>NODE - v10.15.0
  NPM - 6.10.1</p>