Bump symfony/debug from 3.4.27 to 3.4.28

Bumps [symfony/debug](https://github.com/symfony/debug) from 3.4.27 to 3.4.28.
- [Release notes](https://github.com/symfony/debug/releases)
- [Changelog](https://github.com/symfony/debug/blob/master/CHANGELOG.md)
- [Commits](https://github.com/symfony/debug/compare/v3.4.27...v3.4.28)