This PR adds a github actions workflow for deploying new revisions of
the registry on pushes to main.
This means updating the new registry will continue to be as simple as
landing a PR in this repo, but it should only take as long as the docker
container takes to build to see the updates live :)

For now, updates go to dev for manual inspection, but once we're confident in the build process they'll go straight to main as well.

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