title: grunt jshint asks to set esversion to 6 even though it is set to greater
body: <p>In .jshintrc, the <code>esversion</code> is set to 9(to support latest features) <a href="https://jshint.com/docs/options/#esversion" rel="nofollow noreferrer">https://jshint.com/docs/options/#esversion</a></p>
  
  <p>With this, if we run jshint via grunt, we are getting the below error,</p>
  
  <pre><code>'arrow function syntax (=&gt;)' is only available in ES6 (use 'esversion: 6').
  </code></pre>
  
  <p>If we change esversion to 6 back, we are not getting this error, but not able to use async/await. Ideally, esversion 9 should include the features of esversion 6. Is there anything missing here? Any changes to grunt also required? Thanks in advance.</p>
  
  <p>If we run jshint manually, there is no error. This error comes only in grunt.</p>