Updated all dependencies and prepared for PHP 8

classes/DI/SandboxedContainer.php

@@ -20,7 +20,7 @@ class SandboxedContainer implements ContainerInterface {
         $this->container = $container;
     }
 
-    public function has($id) {
+    public function has($id) : bool {
         return $this->container->has($id);
     }