Update rand requirement from 0.5 to 0.6

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/commits)

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot-support

Cargo.toml

@@ -30,7 +30,7 @@ crates-io = "0.17"
 env_logger = "0.5"
 log = "0.4"
 semver = "0.9"
-rand = "0.5"
+rand = "0.6"
 
 [dev-dependencies]
 quickcheck = "0.7"