ci: remove phpunit conflict

Author: soyuka

composer.json

@@ -106,7 +106,6 @@
         "doctrine/persistence": "<1.3",
         "symfony/var-exporter": "<6.1.1",
         "sebastian/comparator": ">=5.0",
-        "phpunit/phpunit": "<9.5",
         "phpspec/prophecy": "<1.15",
         "elasticsearch/elasticsearch": ">=8.0,<8.4"
     },