build: directly require orchestra/testbench instead of graham-campbell/testbench

Author: JaZo

composer.json

@@ -9,9 +9,9 @@
     },
     "require-dev": {
         "friendsofphp/php-cs-fixer": "^3.0",
-        "graham-campbell/testbench": "^5.7",
         "guzzlehttp/guzzle": "^7.3",
         "guzzlehttp/psr7": "^2.1",
+        "orchestra/testbench": "^6.0|^7.0|^8.0",
         "phpunit/phpunit": "^9.5"
     },
     "autoload": {