chore(deps-dev): bump phpunit/phpunit from 9.6.34 to 12.5.22

Bumps [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) from 9.6.34 to 12.5.22.
- [Release notes](https://github.com/sebastianbergmann/phpunit/releases)
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/12.5.22/ChangeLog-12.5.md)
- [Commits](sebastianbergmann/phpunit@9.6.34...12.5.22)

---
updated-dependencies:
- dependency-name: phpunit/phpunit
  dependency-version: 12.5.22
  dependency-type: direct:development
...

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

Author: dependabot[bot]

composer.json

@@ -9,7 +9,7 @@
     },
     "require-dev": {
         "friendsofphp/php-cs-fixer": "^3.0",
-        "phpunit/phpunit": "^9.6",
+        "phpunit/phpunit": "^12.5",
         "wp-phpunit/wp-phpunit": "^6.7",
         "yoast/phpunit-polyfills": "^4.0"
     },