🐛 fix(atom): escape HTML in feed summary

HTML now shows clear,
Escaping tamed, data pure,
Feed sings, have no fear.

templates/atom.xml

@@ -39,9 +39,9 @@
         <link rel="alternate" href="{{ page.permalink | safe }}" type="text/html"/>
         <id>{{ page.permalink | safe }}</id>
         {% if page.summary -%}
-            <summary type="html">{{ page.summary }}</summary>
+            <summary type="html">{{ page.summary | striptags | safe }}</summary>
         {% elif page.description -%}
-            <summary type="html">{{ page.description }}</summary>
+            <summary type="html">{{ page.description | striptags | safe }}</summary>
         {% endif -%}
     </entry>
     {%- endfor %}