Docker builds are failing on ARM, let's see if they work on AMD.
Might be worth waiting until we have less C that needs building
This reverts commit f3894ef9c0.
This PR updates the GH Action docker workflow to crossbuild the docker
image for ARM using QEMU.
This theoratically works but takes about for a clean build 2.5 hours,
which may or may not be tolerable for each commit on `main`.
A action run where the dependencies are already cached needs about 15
minutes with this PR.
