allow for hotfixes

this allow to do hotfixes that bypass the normal release flow, but still creates clear tags.

You can toy around with it on https://git.panter.ch/manul/lab/ci-test/

TBD:

• after a hotfix-tag has been created, the pipeline runs, but does not deploy automatically anywhere, because you probably do not want to override the current stage version. But maybe we automatically deploy to prod right away? That would avoid one manual step and by that time you had plenty of oportunities to review what you fixed.