Increase size of the button 'Filter' and move it into its own div

Signed-off-by: Dylan Aïssi <dylan.aissi@collabora.com>

templates/index.html.jinja2

@@ -131,9 +131,11 @@
     <li class="list-inline-item">
       <a class="text-muted" href="tsv/index.html">🗒️ per-release indices</a>
     </li>
+  </ul>
 
+  <div>
     <div class="dropdown d-inline" data-dropdown="filter">
-      <button class="btn btn-secondary btn-sm dropdown-toggle"
+      <button class="btn btn-secondary dropdown-toggle"
               id="dropdown-button-filter" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
       Filter
       </button>
@@ -183,7 +185,7 @@
         </form>
       </div>
     </div>
-  </ul>
+  </div>
 {% endblock %}
 
 {% block buttons %}