use a PHPUnit bridge version that is compatible with recent PHPUnit releases

Author: xabbuh

composer.json

@@ -16,7 +16,7 @@
  "php-http/client-common": "^1.9 || ^2.0"
  },
  "require-dev": {
- "symfony/phpunit-bridge": "^5.3",
+ "symfony/phpunit-bridge": "^6.4.1",
  "guzzlehttp/psr7": "^2.1"
  },
  "autoload": {