Unblock PHPUnit - add it as a dev dependency (#20)

Author: bocharsky-bw

composer.json

@@ -17,10 +17,8 @@
         "symfony/filesystem": "^6.3|^7.0",
         "symfony/framework-bundle": "^6.3|^7.0",
         "symfony/phpunit-bridge": "^6.3.9|^7.0",
-        "phpstan/phpstan": "^1.10.39"
-    },
-    "conflict": {
-        "phpunit/phpunit": ">=10"
+        "phpstan/phpstan": "^1.10.39",
+        "phpunit/phpunit": "^9.6"
     },
     "minimum-stability": "dev",
     "autoload": {