move response logic to new view controller

app/View/ViewController.php

@@ -0,0 +1,14 @@
+<?php
+
+namespace App\View;
+
+use Psr\Http\Message\ResponseInterface as Response;
+use Slim\Views\Twig;
+
+class ViewController
+{
+    public function admin(Response $response, Twig $view): Response
+    {
+        return $view->render($response, 'admin.html.twig', []);
+    }
+}