Bump php-mock/php-mock-phpunit from 2.8.0 to 2.9.0 (#2131)

Bumps [php-mock/php-mock-phpunit](https://github.com/php-mock/php-mock-phpunit) from 2.8.0 to 2.9.0.
- [Release notes](https://github.com/php-mock/php-mock-phpunit/releases)
- [Commits](php-mock/php-mock-phpunit@2.8.0...2.9.0)

---
updated-dependencies:
- dependency-name: php-mock/php-mock-phpunit
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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