title: Sort DRF serializer output of DictField by key
body: <p>I have a Django Rest Framework serializer that uses a <code>DictField</code>:</p>
  
  <pre><code>class FlatArticleSerializer(Serializer):
      attributes = DictField(child=FlatArticleAttributeSerializer())
  </code></pre>
  
  <p>The output is all the time different, since the attributes are a dictionary, which is by definition not sorted. Is there a way to sort these in the output nevertheless, alphabetically on string for instance?</p>