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] <support@dependabot.com>

Author: dependabot-support

crates/stdsimd/Cargo.toml

@@ -26,7 +26,7 @@ cfg-if = "0.1"
 [dev-dependencies]
 auxv = "0.3.3"
 quickcheck = "0.6"
-rand = "0.4"
+rand = "0.5"
 cupid = "0.5.0"
 
 [[example]]