Show days until holiday on holidays page

templates/holiday_list.html

@@ -10,8 +10,9 @@
     <tr>
       {% if loop.first or item.date != loop.previtem.date %}
         <td class="text-end">{{ display_date(item.date) }}</td>
+        <td>in {{ (item.date - today).days }} days</td>
       {% else %}
-        <td></td>
+        <td colspan="2"></td>
       {% endif %}
       <td>{{ country.flag }} {{ country.name }}</td>
       <td>{{ item.display_name }}</td>