fixed mistake in post list template

date for the post is now correctly displayed

src/zona/data/templates/post_list.html

@@ -9,7 +9,7 @@
 {% if post_list %}
   <ul>
     {% for item in post_list %}
-      <li><small><time datetime="{{ metadata.date | safe }}">{{ metadata.date | safe}}</time></small>: <a href="/{{ item.url }}">{{ item.metadata.title }}</a></li>
+      <li><small><time datetime="{{ item.metadata.date | safe }}">{{ item.metadata.date | safe}}</time></small>: <a href="/{{ item.url }}">{{ item.metadata.title }}</a></li>
     {% endfor %}
   </ul>
 {% endif %}