V1 Version from the tag name

[jeffeb3]

https://forum.v1engineering.com/t/marlinbuild-again/19157/83?u=jeffeb3

I’m willing to bet that ${{ github.event.release.tag_name }} works.

This issue is so I don't forget to do this.

1. Make it based completely on an env variable.
2. Make a reasonable default value to make it clear we aren't using a release.
3. Try hard to not screw up releases anymore.