chore(dependencies): Bump secure_headers from 5.0.3 to 5.0.4
chore(dependencies): Bump secure_headers from 5.0.3 to 5.0.4

Bumps [secure_headers](https://github.com/twitter/secureheaders) from 5.0.3 to 5.0.4.
- [Changelog](https://github.com/twitter/secureheaders/blob/master/CHANGELOG.md)
- [Commits](https://github.com/twitter/secureheaders/compare/v5.0.3...v5.0.4)
ministryofjustice/prison-visits-public,ministryofjustice/prison-visits-public,ministryofjustice/prison-visits-public,ministryofjustice/prison-visits-public