Auto-update the major version tag upon release #32
Description
Whenever we release a new version, e.g. v2.4.1, we also need to update the major version tag, in this case v2, to point to the new release (also see github recommendations).
Unfortunately, this is easy to forget. As a result, we can get some unwanted surprises in dependent repos, such as thinking the latest version of the reusable workflow is used, while it is actually still using the old version.
Therefore, we need to automate the update of the major version tag.