Bump secure_headers from 3.6.4 to 3.6.5 (#938)
Bump secure_headers from 3.6.4 to 3.6.5 (#938)

Bumps [secure_headers](https://github.com/twitter/secureheaders) from 3.6.4 to 3.6.5.
- [Changelog](https://github.com/twitter/secureheaders/blob/master/CHANGELOG.md)
- [Commits](https://github.com/twitter/secureheaders/compare/v3.6.4...v3.6.5)
ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2,ministryofjustice/prison-visits-2