release GitHub workflow takes over an hour

[nf-s]

I think it should only take 7-8 minutes

[pjonsson]

@nf-s it takes us 6 minutes to build the docker image in this repository on x86-64 for x86-64. The release workflow also builds images for linux/arm64 through emulation. I can't tell if 10x slowdown is expected, but here's a link to someone getting a 22x speedup from switching to real hardware: https://actuated.dev/blog/native-arm64-for-github-actions