Update dependency phpunit/phpunit to v12

Author: renovate[bot]

packages/flags/composer.json

@@ -23,7 +23,7 @@
     },
     "require-dev": {
         "orchestra/testbench": "^9.0",
-        "phpunit/phpunit": "^10.0"
+        "phpunit/phpunit": "^12.0"
     },
     "autoload": {
         "psr-4": {