Update rand requirement to 0.5
Update rand requirement to 0.5

Updates the requirements on [rand](https://github.com/rust-lang-nursery/rand) to permit the latest version.
- [Release notes](https://github.com/rust-lang-nursery/rand/releases)
- [Changelog](https://github.com/rust-lang-nursery/rand/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-lang-nursery/rand/commits/0.5.3)

Signed-off-by: dependabot[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
rust-lang/stdarch,rust-lang/stdarch,rust-lang/stdarch,rust-lang/stdarch,rust-lang/stdarch