<div class="text-muted">
  Published:
  <span itemprop="datePublished" content="{{ post.published_date|date:"c" }}">
    {{ post.published_date }}
  </span>
  {% if post.updated_date != post.published_date %}
    Updated:
    <span itemprop="dateModified" content="{{ post.updated_date|date:"c" }}">
      {{ post.updated_date }}
    </span>
  {% endif %}
</div>
