Use secure protocol in xmlns

Author: sshcli

docs/_templates/page.html

@@ -76,7 +76,7 @@
     <div class="content">
       <div class="article-container">
         <a href="#" class="back-to-top muted-link">
-          <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
+          <svg xmlns="https://www.w3.org/2000/svg" viewBox="0 0 24 24">
             <path d="M13 20h-2V8l-5.5 5.5-1.42-1.42L12 4.16l7.92 7.92-1.42 1.42L13 8v12z"></path>
           </svg>
           <span>{% trans %}Back to top{% endtrans %}</span>
@@ -245,4 +245,4 @@
     </aside>
   </div>
 </div>
-{%- endblock %}
+{%- endblock %}