Update rand requirement from 0.3.14 to 0.6.5
Update rand requirement from 0.3.14 to 0.6.5

Updates the requirements on [rand](https://github.com/rust-random/rand) to permit the latest version.
- [Release notes](https://github.com/rust-random/rand/releases)
- [Changelog](https://github.com/rust-random/rand/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-random/rand/compare/0.3.14...0.6.5)
cstorey/phi-accrual-rs