Update figure

Author: anyohu

_includes/figure

@@ -1,7 +1,7 @@
 <figure class="{{ include.class }}">
   {%- if include.popup -%}<a href="{{ include.image_path | relative_url }}" class="image-popup"{% if include.caption %} title="{{ include.caption | markdownify | strip_html }}"{% endif %}>{%- endif -%}
   <img src="{{ include.image_path | relative_url }}"
-       alt="{% if include.alt %}{{ include.alt }}{% endif %}">
+       alt="{% if include.alt %}{{ include.alt | escape_once }}{% endif %}">
   {%- if include.popup -%}</a>{%- endif -%}
   {%- if include.caption -%}
     <figcaption>