chore(deps): update dependency phpunit/phpunit to v12

Author: renovate[bot]

providers/Flagsmith/composer.json

@@ -40,7 +40,7 @@
     "phpstan/phpstan": "~1.10.0",
     "phpstan/phpstan-mockery": "^1.0",
     "phpstan/phpstan-phpunit": "^1.1",
-    "phpunit/phpunit": "^9.6",
+    "phpunit/phpunit": "^12.0",
     "psalm/plugin-mockery": "^0.11.0",
     "psalm/plugin-phpunit": "^0.18.0",
     "ramsey/coding-standard": "^2.0.3",

providers/GoFeatureFlag/composer.json

@@ -23,7 +23,7 @@
     "psr/http-message": "^2.0"
   },
   "require-dev": {
-    "phpunit/phpunit": "^9",
+    "phpunit/phpunit": "^12",
     "mockery/mockery": "^1.6",
     "spatie/phpunit-snapshot-assertions": "^4.2",
     "phan/phan": "^5.4",