build(deps-dev): bump phpunit/phpunit (simplesamlphp#2551)

Bumps the development-dependencies group with 1 update: [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit).


Updates `phpunit/phpunit` from 11.5.42 to 11.5.43
- [Release notes](https://github.com/sebastianbergmann/phpunit/releases)
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/11.5.43/ChangeLog-11.5.md)
- [Commits](sebastianbergmann/phpunit@11.5.42...11.5.43)

---
updated-dependencies:
- dependency-name: phpunit/phpunit
  dependency-version: 11.5.43
  dependency-type: indirect
  update-type: version-update:semver-patch
  dependency-group: development-dependencies
...

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Author: dependabot[bot]