title: vue2-datepicker can not disable future dates
body: <pre><code>**Template **
  
  &lt;date-picker
              :disabled="form.type != 1"
              input-class="form-control"
              format="YYYY-MM-DD"
              range
              v-model="form.date"
              valueType="format"
              :not-after="disabledAfter"&gt;
  &lt;/date-picker&gt;
  </code></pre>
  
  <p><strong>Scripts</strong> Vue2-Datepicker version 3.3.0</p>
  
  <pre><code>data(){
      return{
           disabledAfter: new Date(2020, 4, 30),
      }
  }
  </code></pre>
  
  <p>Can not disable future dates. Is it about version?</p>