Make content type html in Atom feed

Author: bennuttall

templates/atom.pt

@@ -10,13 +10,13 @@
   <updated>${now.isoformat(timespec="seconds")}</updated>
 
   <entry tal:repeat="post posts">
-    <title><![CDATA[${post.title}]]></title>
+    <title><![CDATA[${structure:post.title}]]></title>
     <link href="https://blog.piwheels.org/${post.link}/" />
     <id>https://blog.piwheels.org/${post.link}</id>
     <published>${post.published.isoformat(timespec="seconds")}</published>
     <updated>${post.modified.isoformat(timespec="seconds")}</updated>
     <category tal:repeat="tag post.tags" term="${tag}" />
-    <summary><![CDATA[${post.excerpt}]]></summary>
-    <content><![CDATA[${structure:post.html}]]></content>
+    <summary><![CDATA[${structure:post.excerpt}]]></summary>
+    <content type="html"><![CDATA[${structure:post.html}]]></content>
   </entry>
 </feed>