Merge pull request #551 from WyriHaximus-labs/1.x-update-test-environment-for-PHP-7.2

[1.x] Update test environment for PHP 7.2 to compatible PHPUnit version

Author: clue

composer.json

@@ -39,7 +39,7 @@
         "clue/http-proxy-react": "^1.8",
         "clue/reactphp-ssh-proxy": "^1.4",
         "clue/socks-react": "^1.4",
-        "phpunit/phpunit": "^9.6 || ^5.7 || ^4.8.36",
+        "phpunit/phpunit": "^9.6 || ^8.5 || ^5.7 || ^4.8.36",
         "react/async": "^4.2 || ^3 || ^2",
         "react/promise-stream": "^1.4",
         "react/promise-timer": "^1.11"