v1.2.0

• Bumped @actions/core from 1.2.6 to 1.2.7
• Bumped @actions/io from 1.0.2 to 1.1.0
• Updated the repo-token input to be optional and defaulted it to GITHUB_TOKEN. If you're already using this value, or not using the only-changed-files option, you can remove this setting from your workflow.
• Updated the output target from es6 to es2019
• Added a new version input to allow picking the cli version of dotnet-format to use. Currently this defaults to 3 and is the only version supported. A future update will add support for versions 4 and 5.