Bump symfony/yaml from 4.2.8 to 4.2.9
Bump symfony/yaml from 4.2.8 to 4.2.9

Bumps [symfony/yaml](https://github.com/symfony/yaml) from 4.2.8 to 4.2.9.
- [Release notes](https://github.com/symfony/yaml/releases)
- [Changelog](https://github.com/symfony/yaml/blob/master/CHANGELOG.md)
- [Commits](https://github.com/symfony/yaml/compare/v4.2.8...v4.2.9)
linuxjuggler/database-backup