Update rand_distr requirement from 0.4 to 0.5

Updates the requirements on [rand_distr](https://github.com/rust-random/rand_distr) to permit the latest version.
- [Release notes](https://github.com/rust-random/rand_distr/releases)
- [Changelog](https://github.com/rust-random/rand_distr/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-random/rand_distr/compare/0.4.0...0.5.1)

---
updated-dependencies:
- dependency-name: rand_distr
  dependency-version: 0.5.1
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -26,7 +26,7 @@ ndarray = { version = "0.15", optional = true }
 num-traits = "0.2.12"
 num = "0.4"
 rand = { version = "0.8.5", default-features = false, features = ["small_rng"] }
-rand_distr = { version = "0.4", optional = true }
+rand_distr = { version = "0.5", optional = true }
 serde = { version = "1", features = ["derive"], optional = true }
 ordered-float = "5.1.0"