Tags, releases and Docker Images

[shipilovds]

done

[shipilovds]

https://github.com/shipilovds/amneziawg-exporter/issues/2

[tiaga]

Let's avoid hardcode and start push Docker Images only if a semver tag was pushed to the repo. So, we should set the corresponding trigger:

on:
    tags:
      - '[0-9]+.[0-9]+.[0-9]+'

and push only if tag was provided:

      - name: Build
        uses: docker/build-push-action@v6
        with:
          push: ${{ contains(github.ref, 'refs/tags/') }} # push if tag was set