chore(deps-dev): bump php-mock/php-mock-phpunit from 2.13.1 to 2.15.0

Bumps [php-mock/php-mock-phpunit](https://github.com/php-mock/php-mock-phpunit) from 2.13.1 to 2.15.0.
- [Release notes](https://github.com/php-mock/php-mock-phpunit/releases)
- [Commits](php-mock/php-mock-phpunit@2.13.1...2.15.0)

---
updated-dependencies:
- dependency-name: php-mock/php-mock-phpunit
  dependency-version: 2.15.0
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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Author: dependabot[bot]