Add option to change version of all workspaces together

Do you want to request a feature or report a bug?

Feature

What is the current behavior? yarn version only changes current package.json file

What is the expected behavior? yarn version should have to option to change the version in all workspaces, or a version command should be added to yarn workspaces.

e.g. yarn workspaces version will change the version in all workspaces to the new one.

This will be useful for packages that you always want to stay in sync, and get released together.