Create a GitHub Action workflow that validate Terraform Setup guide

[gianarb]

Create a similar test suite as the one we use to validate Vagrant but for Terraform on Equinix Metal

[gianarb]

We can't do until #1 is over

[invidian]

#1 is now done, so this can be closed too? I see https://github.com/tinkerbell/sandbox/runs/1662739685?check_suite_focus=true being run.

With that, v0.1.0 milestone can be closed as well.

[gianarb]

This issue to be closed requires a GitHub Action pipeline that validate that the Terrafrom Setup guide works. It is not done yet :( let me change the title

[invidian]

Ah, my bad. We only have a Vagrant check. Sorry for the noise :)

[tstromberg]

I think this sounds like a useful request to prevent future breakage. Any volunteers?