Fix related posts' date.

cotes2020 · cotes2020 · commit b504dddce82e · 2019-11-21T22:43:01.000+08:00
diff --git a/_includes/related-posts.html b/_includes/related-posts.html
@@ -52,7 +52,7 @@ <h3 class="pt-2 mt-1 mb-4" data-toc-skip>Related Posts</h3>
           <div class="card-body">
             <span class="timeago small">
                 {{ post.date | date: POST_DATE }}
-                <i class="hidden">{{ page.date | date_to_xmlschema }}</i>
+                <i class="hidden">{{ post.date | date_to_xmlschema }}</i>
             </span>
             <h3 class="pt-0 mt-2 mb-3" data-toc-skip>{{ post.title }}</h3>
             <div class="text-muted small">
