deps: update getrandom requirement from 0.3.0 to 0.4.0

Updates the requirements on [getrandom](https://github.com/rust-random/getrandom) to permit the latest version.
- [Changelog](https://github.com/rust-random/getrandom/blob/master/CHANGELOG.md)
- [Commits](rust-random/getrandom@v0.3.0...v0.4.0)

---
updated-dependencies:
- dependency-name: getrandom
  dependency-version: 0.4.0
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Cargo.toml

@@ -17,7 +17,7 @@ exclude = [".gitignore", ".travis.yml", "tests/*"]
 subtle = { version = "^2.2.2", default-features = false }
 zeroize = { version = "1.1.0", default-features = false }
 fiat-crypto = { version = "0.3.0", default-features = false }
-getrandom = { version = "0.3.0", optional = true }
+getrandom = { version = "0.4.0", optional = true }
 ct-codecs = { version = "1.1.1", optional = true }
 
 [dependencies.serde]