build(deps): update rand requirement from 0.7.3 to 0.8.5

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](rust-random/rand@0.7.3...0.8.5)

---
updated-dependencies:
- dependency-name: rand
  dependency-type: direct:production
...

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

Cargo.toml

@@ -21,7 +21,7 @@ csv = "1.0.2"
 rustc-serialize = "0.3"
 newtype_derive = "0.1"
 custom_derive = "0.1"
-rand = "0.7.3"
+rand = "0.8.5"
 rand_core = "0.5.1"
 serde = "1.0"
 serde_derive = "1.0"