Bump phpunit/phpunit from 9.0.0 to 9.4.0

Bumps [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) from 9.0.0 to 9.4.0.
- [Release notes](https://github.com/sebastianbergmann/phpunit/releases)
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/master/ChangeLog-9.4.md)
- [Commits](sebastianbergmann/phpunit@9.0.0...9.4.0)

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

Author: dependabot[bot]