Add SubAdminMiddleware back

Removed by mistake in #1946

Signed-off-by: Lukas Reschke <lukas@statuscode.ch>

settings/Application.php

@@ -69,6 +69,8 @@ class Application extends App {
 
 		// Register Middleware
 		$container->registerAlias('SubadminMiddleware', SubadminMiddleware::class);
+		$container->registerMiddleWare('SubadminMiddleware');
+
 		/**
 		 * Controllers
 		 */