Bump phpunit/phpunit in the composer group across 1 directory

Bumps the composer group with 1 update in the / directory: [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit).


Updates `phpunit/phpunit` from 11.2.6 to 11.5.50
- [Release notes](https://github.com/sebastianbergmann/phpunit/releases)
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/11.5.50/ChangeLog-11.5.md)
- [Commits](sebastianbergmann/phpunit@11.2.6...11.5.50)

---
updated-dependencies:
- dependency-name: phpunit/phpunit
  dependency-version: 11.5.50
  dependency-type: direct:development
  dependency-group: composer
...

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

Author: dependabot[bot]