title: Update input value after validation
body: <p>I’m new to Vue.</p>
  <p>I would like to know if it is possible to update the input value after running a custom validation in Vuelidate. I have an input field for postcode. I want to return the postcode with the correct format in case the user forgets to put a whitespace, and update the input field with the correct value, e.g.</p>
  <p>user input = XXXXXX<br/>
  returned output = XXX XXX</p>
  <p>Sample code</p>
  <pre class="lang-js prettyprint-override"><code>export default {
    ...
    validations: {
      postcode: {
        required,
        maxLength: maxLength(10),
        validatePostcode: (value) =&gt; {
          const result = customValidators.validatePostcode(value);
          if (result !== false) {
            if (result !== value) {
              // UPDATE THE INPUT VALUE HERE WITH THE CORRECT POSTCODE FORMAT
            }
            return true;
          }
          return false;
        }
      }
    }
    ...
  }
  </code></pre>