This also changes the container version numbers in the tag from unix
timestamps to the abbreviated commit hash for the workflow. This ensures
that the amd64 and arm64 containers have the same tag.
For amd64 we now generate 4 tags:
* ghcr.io/llvm/ci-ubuntu-22.04:latest
* ghcr.io/llvm/ci-ubuntu-22.04:$GITHUB_SHA
* ghcr.io/llvm/amd64/ci-ubuntu-22.04:latest
* ghcr.io/llvm/amd64/ci-ubuntu-22.04:$GITHUB_SHA
For arm64 we generate 2 tags:
* ghcr.io/tstellar/arm64v8/ci-ubuntu-22.04:latest
* ghcr.io/tstellar/arm64v8/ci-ubuntu-22.04:$GITHUB_SHA
89001d1de8