fix blog post blurb link (#965)

server/templates/static/homepage.html

@@ -50,7 +50,7 @@ <h2>{% trans %}What's new{% endtrans %}</h2>
       <dd>
         {# TRANSLATORS: Blog post entry. Please take care to maintain valid <a> tags in translation. See this string in action at https://datacommons.org #}
         {% trans blog_url="https://docs.datacommons.org/2021/06/01/updates.html",project="Data Commons" -%}
-        We have launched exciting new features, including internationalization support, a new graph browser and scatter plot explorer, new Stats API, updated documentation, and new data. <a href=%(blog_url)s>Read our blog post for more details</a>.
+        We have launched exciting new features, including internationalization support, a new graph browser and scatter plot explorer, new Stats API, updated documentation, and new data. <a href={{blog_url}}>Read our blog post for more details</a>.
         {%- endtrans %}
       </dd>
     </dl>