allow php8.1 in tests

Author: brecht.vermeersch

composer.json

@@ -27,7 +27,7 @@
   },
   "require-dev": {
     "laravel/pint": "^1.17",
-    "orchestra/testbench": "^9.2",
+    "orchestra/testbench": "^8.1|^9.2",
     "phpstan/phpstan": "^1.11",
     "phpstan/phpstan-deprecation-rules": "^1.2",
     "phpstan/phpstan-strict-rules": "^1.6"