make 'modern' template default for new websites

ot_admin/Classes/Controller/SiteController.php

@@ -67,7 +67,7 @@ class SiteController extends ActionController
     private const CTYPE_SITEMAP = 'menu_sitemap';
 
     // Default values
-    private const DEFAULT_THEME = 'Classic';
+    private const DEFAULT_THEME = 'Modern';
     private const DEFAULT_COLOR = 'light-blue';
 
     // BE rights
@@ -1996,7 +1996,8 @@ class SiteController extends ActionController
             'organization_id' => $organization->getId(),
             'subdomain' => $organization->getSubDomain(),
             'locale' => 'fr_FR',
-            'organization_name' => $organization->getName()
+            'organization_name' => $organization->getName(),
+            'template' => self::DEFAULT_THEME
         ];
 
         $queryBuilder = $this->connectionPool->getQueryBuilderForTable('ot_websites');