build(deps-dev): bump phpunit/phpunit in the dependencies group

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


Updates `phpunit/phpunit` from 10.5.19 to 10.5.20
- [Release notes](https://github.com/sebastianbergmann/phpunit/releases)
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/10.5.20/ChangeLog-10.5.md)
- [Commits](sebastianbergmann/phpunit@10.5.19...10.5.20)

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

Signed-off-by: dependabot[bot] <[email protected]>