Adjust make docker and Dockerfile to have clean version for tags

[simu]

Not sure why git describe --tags --always --dirty --match=v* always has suffix -dirty for the container image build even when run on a tagged commit in a clean working directory. The command correctly returns just the tag in the Makefile for the same checkout state, so we simply introduce a VERSION build argument in the Dockerfile to use the correct command output for the final binary built in the container image.

Checklist

• Keep pull requests small so they can be easily reviewed.
• Categorize the PR by setting a good title and adding one of the labels:
  bug, enhancement, documentation, change, breaking, dependency
  as they show up in the changelog