Update google-cloud-kms to 1.2.1

Created by: pyup-bot

This PR updates google-cloud-kms from 1.0.0 to 1.2.1.

The bot wasn't able to find a changelog for this release. Got an idea?

Links

• PyPI: https://pypi.org/project/google-cloud-kms
• Repo: https://github.com/GoogleCloudPlatform/google-cloud-python