<h1 class="post-title"><a href="{{ .Permalink }}">{{ .Title }}</a></h1>
<time class="post-date" {{ printf "datetime=%s" (.Date.Format "2006-01-02T15:04:05-0700") | safeHTMLAttr }}>
  {{ .Date.Format "Jan 2, 2006" }}
</time>
<ul class="tags">
  {{ range .Params.tags }}
    <li><a href="{{ "tags/" | absLangURL }}{{ . | urlize }}">{{ . }}</a> </li>
  {{ end }}
</ul>

<h1 class="post-title"><a href="{{ .Permalink }}">{{ .Title }}</a></h1>
<time class="post-date" {{ printf "datetime=\"%s\"" (.Date.Format "2006-01-02T15:04:05-0700") | safeHTMLAttr }}>
  {{ .Date.Format "Jan 2, 2006" }}
</time>
<ul class="tags">
  {{ range .Params.tags }}
    <li><a href="{{ "tags/" | absLangURL }}{{ . | urlize }}">{{ . }}</a> </li>
  {{ end }}
</ul>

Add missing quotes around datetime attribute
Add missing quotes around datetime attribute
