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": "^5.4.33 || ~6.3.10 || ^6.4.1",
         "guzzlehttp/psr7": "^2.1"
     },
     "autoload": {