Update phpunit/phpunit requirement from ^9.3 || ^10.0 to ^9.3 || ^10.0 || ^12.0

---
updated-dependencies:
- dependency-name: phpunit/phpunit
  dependency-version: 12.3.15
  dependency-type: direct:development
...

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

Author: dependabot[bot]

composer.json

@@ -23,7 +23,7 @@
     },
     "require-dev": {
         "phpstan/phpstan": "^2.0",
-        "phpunit/phpunit": "^9.3 || ^10.0",
+        "phpunit/phpunit": "^9.3 || ^10.0 || ^12.0",
         "squizlabs/php_codesniffer": "^3.5.0 || ^4.0.0"
     },
     "autoload": {