composer(deps-dev): bump phpstan/phpstan-phpunit from 2.0.21 to 2.1.1

Bumps [phpstan/phpstan-phpunit](https://github.com/phpstan/phpstan-phpunit) from 2.0.21 to 2.1.1.
- [Release notes](https://github.com/phpstan/phpstan-phpunit/releases)
- [Commits](phpstan/phpstan-phpunit@2.0.21...2.1.1)

---
updated-dependencies:
- dependency-name: phpstan/phpstan-phpunit
  dependency-version: 2.1.1
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

composer.json

@@ -15,7 +15,7 @@
         "friendsofphp/php-cs-fixer": "^3.95.27",
         "phpstan/extension-installer": "^1.4",
         "phpstan/phpstan": "^2.3",
-        "phpstan/phpstan-phpunit": "^2.0",
+        "phpstan/phpstan-phpunit": "^2.1",
         "phpunit/phpunit": "^11.5.50"
     },
     "autoload": {