fix: github actions runner roller for linux

[jkleinsc]

• Followup to build: roll github actions runners automatically #147.
  When the GitHub Actions runner roller ran, it accidentally tried to update the linux containers as follows:
  FROM:

image: ghcr.io/actions/actions-runner:2.325.0@sha256:b865e3f046f0a92a4b936ae75c5bc5615b99b64eb4801b0e5220f13f8867d6b8

TO:

image: sha256:b865e3f046f0a92a4b936ae75c5bc5615b99b64eb4801b0e5220f13f8867d6b8 

This PR fixes that issue and also updates the tests to better verify the GitHub Actions roller.