refactor: remove unused variable

Author: kenjis

system/Router/RouteCollection.php

@@ -1641,7 +1641,7 @@ public function getRegisteredControllers(?string $verb = '*'): array
 
         if ($verb === '*') {
             foreach ($this->defaultHTTPMethods as $tmpVerb) {
-                foreach ($this->routes[$tmpVerb] as $routeKey => $route) {
+                foreach ($this->routes[$tmpVerb] as $route) {
                     $controller = $this->getControllerName($route['handler']);
                     if ($controller !== null) {
                         $controllers[] = $controller;