Ignore existing Version on canary release.

**Is your feature request related to a problem? Please describe.**

Currently when running multiple `auto canary` or `auto shipit` commands on one git commit in an pr (eg. because you have github actions triggering on "labeld" and "push" in pull requests) , the second one always fails with 'version already exists'.

**Describe the solution you'd like**

As the version already includes the git commit hash, there should only ever be a clash when running on the same commit, which should be ok.
So it would be awesome to be able to tell auto to ignore that version allready exists error.

**Describe alternatives you've considered**

If this should be the new default is not up to me, and I can see it either way tbh.
As this would be a breaking change however, I am in favor for a flag / configuration that ignores this specific error.