Symfony 5 support: Return 'assets' dir correctly (#24)

By default, return 'assets' for anything above Symfony 4. Previously, it was incorrectly returning 'web' for Symfony 5.

Author: Ivan-Perez

DependencyInjection/Configuration.php

@@ -55,10 +55,10 @@ public function getConfigTreeBuilder()
     private function getAssetsDir()
     {
         switch (Kernel::MAJOR_VERSION) {
-            case 4:
-                return 'assets';
-            default:
+            case 3:
                 return 'web';
+            default:
+                return 'assets';
         }
     }
 }