Install latest buildx to ensure GHA cache works

[huonw]

No description provided.

[huonw]

Still seeing:

#9 preparing build cache for export done
#9 ERROR: This legacy service is shutting down, effective April 15, 2025. Migrate to the new service ASAP. For more information: https://gh.io/gha-cache-sunset
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 > importing cache manifest from gha:13323955006386176775:
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 > exporting to GitHub Actions Cache:
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ERROR: failed to solve: This legacy service is shutting down, effective April 15, 2025. Migrate to the new service ASAP. For more information: https://gh.io/gha-cache-sunset

This was vaguely attempting to follow https://docs.docker.com/build/ci/github-actions/cache/#github-cache, but I've run out of time for the next few days.

[tdyas]

Does https://github.com/docker/setup-docker-action need to be upgraded (redirected from https://github.com/crazy-max/ghaction-setup-docker so we should update the name in any event)?