test: fix: restore require_once that was accidentally deleted

Author: kenjis

system/Test/bootstrap.php

@@ -84,6 +84,11 @@ class_alias('Config\Services', 'CodeIgniter\Services');
 // Initialize and register the loader with the SPL autoloader stack.
 Services::autoloader()->initialize(new Autoload(), new Modules())->register();
 
+// Now load Composer's if it's available
+if (is_file(COMPOSER_PATH)) {
+    require_once COMPOSER_PATH;
+}
+
 // Load environment settings from .env files into $_SERVER and $_ENV
 require_once SYSTEMPATH . 'Config/DotEnv.php';