Bump string from 0.2.0 to 0.2.1
Bump string from 0.2.0 to 0.2.1

Bumps [string](https://github.com/carllerche/string) from 0.2.0 to 0.2.1.
- [Release notes](https://github.com/carllerche/string/releases)
- [Changelog](https://github.com/carllerche/string/blob/master/CHANGELOG.md)
- [Commits](https://github.com/carllerche/string/commits)

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