Update dependency phpunit/phpunit to v12 (#39)

| datasource | package         | from   | to     |
| ---------- | --------------- | ------ | ------ |
| packagist  | phpunit/phpunit | 11.5.7 | 12.0.2 |

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

composer.json

@@ -18,7 +18,7 @@
     "require-dev": {
         "phpstan/phpstan": "^2.1.5",
         "phpstan/phpstan-phpunit": "^2",
-        "phpunit/phpunit": "^11.5.7"
+        "phpunit/phpunit": "^12.0.2"
     },
     "autoload": {
         "psr-4": {