ci: add tests for PHP 8.5

Author: Chris8934

composer.json

@@ -17,9 +17,9 @@
         "guzzlehttp/guzzle": "^7.0"
     },
     "require-dev": {
-        "phpunit/phpunit": "^8.5 || ^9.0 || ^10.0 || ^11.0 || ^12.0",
+        "phpunit/phpunit": "^9.6.31 || ^10.0 || ^11.0 || ^12.0",
         "php-http/client-integration-tests": "^4.0",
-        "phpspec/prophecy-phpunit": "^2.0",
+        "phpspec/prophecy-phpunit": "^2.4",
         "php-http/message-factory": "^1.1"
     },
     "provide": {