build(deps): bump base64 from 0.12.0 to 0.12.1
build(deps): bump base64 from 0.12.0 to 0.12.1

Bumps [base64](https://github.com/marshallpierce/rust-base64) from 0.12.0 to 0.12.1.
- [Release notes](https://github.com/marshallpierce/rust-base64/releases)
- [Changelog](https://github.com/marshallpierce/rust-base64/blob/master/RELEASE-NOTES.md)
- [Commits](https://github.com/marshallpierce/rust-base64/commits)

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