Bump error-chain from 0.12.0 to 0.12.1 (#69)
Bump error-chain from 0.12.0 to 0.12.1 (#69)

Bumps [error-chain](https://github.com/rust-lang-nursery/error-chain) from 0.12.0 to 0.12.1.
- [Release notes](https://github.com/rust-lang-nursery/error-chain/releases)
- [Changelog](https://github.com/rust-lang-nursery/error-chain/blob/master/CHANGELOG.md)
- [Commits](https://github.com/rust-lang-nursery/error-chain/commits)

Signed-off-by: dependabot-preview[bot] <5bdcd3c0d4d24ae3e71b3b452a024c6324c7e4bb@dependabot.com>
alex/ct-tools,alex/ct-tools