Fix post dates

src/_includes/post.njk

@@ -5,7 +5,7 @@ includePrism: true
 <main class="wrapper-md stack-lg">
     <article class="stack-md h-entry">
         <h1 class="p-name"><a href="{{ url }}" class="u-url">{{ title | safe }}</a></h1>
-        <p class="published">Published: <time class="dt-published" datetime="{{ date | dateToRfc3339 }}">{{ date | dateDisplay }}</time></p>
+        <p class="published">Published: <time class="dt-published" datetime="{{ page.date | dateToRfc3339 }}">{{ page.date | dateDisplay }}</time></p>
         <div class="e-content stack-md">
         {{ content | safe }}
         </div>