Add Laravel 9 support

Author: mnabialek

composer.json

@@ -2,7 +2,7 @@
   "name": "mnabialek/laravel-test-css",
   "description": "Allows to add some custom CSS styles when running tests",
   "require": {
-    "laravel/framework": "5.*|6.*|7.*|8.*"
+    "laravel/framework": "5.*|6.*|7.*|8.*|9.*"
   },
   "require-dev": {
     "friendsofphp/php-cs-fixer": "^2.13"