[DEPS]: Bump wp-phpunit/wp-phpunit from 5.7.2 to 5.8.0

Bumps [wp-phpunit/wp-phpunit](https://github.com/wp-phpunit/wp-phpunit) from 5.7.2 to 5.8.0.
- [Release notes](https://github.com/wp-phpunit/wp-phpunit/releases)
- [Commits](wp-phpunit/wp-phpunit@5.7.2...5.8.0)

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

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