Update rand requirement from 0.8 to 0.9

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@0.8.0...0.9.0)

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

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

Cargo.toml

@@ -65,7 +65,7 @@ hyperdual = "1.1"
 light-curve-common = "0.1.0"
 plotters = { version = "0.3.5", default-features = false, features = ["errorbar", "line_series", "ttf"] }
 plotters-bitmap = "0.3.3"
-rand = "0.8"
+rand = "0.9"
 rand_distr = "0.4"
 rayon = "1.5"
 realfft = "3.1"