Fix under_construction page for fronentd lint

src/plainui/jinja2/plainui/under_construction.html.j2

-{% extends "plainui/base.html" %}
-{% import "plainui/components/integrations.html" as integrations %}
-{% import "plainui/components/markdown.html" as markdownMacro %}
-{% import "plainui/components/nav.html" as navMacro with context %}
-{% import "plainui/components/three_cards.html" as threeCardsMacro %}
-{% import "plainui/components/buttons.html" as buttonsMacro %}
-{% import "plainui/components/list_events.html.j2" as list_events with context %}
+{% extends "plainui/base.html.j2" %}
+{% import "plainui/components/nav.html.j2" as navMacro with context %}
 
-{% block title %}{{ conf.name }} - {{ _("Under Construction") }}{% endblock %}
-{% block content %}
+{% block title %}
+  {{ conf.name }} - {{ _("Under Construction") }}
+{% endblock title %}
 
+{% block content %}
   {{ navMacro.top_nav(_("Under Construction") ) }}
 
   <div class="hub-vlayout">
@@ -21,5 +18,4 @@
       </div>
     </div>
   </div>
-
 {% endblock content %}