Bump rand_chacha from 0.2.1 to 0.2.2 (#475)
Bump rand_chacha from 0.2.1 to 0.2.2 (#475)

Bumps [rand_chacha](https://github.com/rust-random/rand) from 0.2.1 to 0.2.2.
- [Release notes](https://github.com/rust-random/rand/releases)
- [Changelog](https://github.com/rust-random/rand/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-random/rand/compare/rand_chacha-0.2.1...rand_chacha-0.2.2)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>

Co-authored-by: dependabot-preview[bot] <6a4c1c4838f800d1998274cd5234e1f65c55e90c@users.noreply.github.com>
alex/ct-tools,alex/ct-tools