Update rand_chacha requirement from 0.3 to 0.9

Updates the requirements on [rand_chacha](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@rand_chacha-0.3.0...0.9.0)

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

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

Cargo.toml

@@ -16,7 +16,7 @@ ark-bls12-381 = { version = "0.5" }
 ark-ec = { version = "0.5", default-features = false }
 ark-ff = { version = "0.5", default-features = false }
 ark-serialize = { version = "0.5", default-features = false }
-rand_chacha = { version = "0.3" }
+rand_chacha = { version = "0.9" }
 
 [dev-dependencies]
 criterion = "0.5"