Update sensiolabs/security-checker requirement
Update sensiolabs/security-checker requirement

Updates the requirements on [sensiolabs/security-checker](https://github.com/sensiolabs/security-checker) to permit the latest version.
- [Release notes](https://github.com/sensiolabs/security-checker/releases)
- [Commits](https://github.com/sensiolabs/security-checker/commits/v6.0.0)
Aerendir/PHPValueObjects,Aerendir/PHPValueObjects