title: limiting file extension in django form file upload
body: <p>I have forms.Form in django. In this form there is a forms.FileField. This field is rendered in html as</p>
  
  <pre><code>&lt;input id="id_upload-loaded_file" name="upload-loaded_file" type="file"&gt;
  </code></pre>
  
  <p>I need to add accepted files only with ".zip" extension  so that form will be rendered as</p>
  
  <pre><code>&lt;input id="id_upload-loaded_file" name="upload-loaded_file" type="file" accept=".zip"&gt;
  </code></pre>
  
  <p>How can I add accepted file extension attribute in django?</p>