Bump povils/phpmnd from 3.3.0 to 3.4.0 in /tools/phpmnd

Bumps [povils/phpmnd](https://github.com/povils/phpmnd) from 3.3.0 to 3.4.0.
- [Release notes](https://github.com/povils/phpmnd/releases)
- [Changelog](https://github.com/povils/phpmnd/blob/master/CHANGELOG.md)
- [Commits](povils/phpmnd@v3.3.0...v3.4.0)

---
updated-dependencies:
- dependency-name: povils/phpmnd
  dependency-type: direct:development
  update-type: version-update:semver-minor
...

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