Update docker image to runtime 46; reduces build times by a lot, especially on ARM64
Update docker/setup-qemu-action to fix a warning
A warning about outdated artifact workflow remains; however, it comes from the flatpak action (I do not invoke it directly), so nothing can be done on my end here.
A warning about outdated artifact workflow remains; however, it comes from the flatpak action (I do not invoke it directly), so nothing can be done on my end here.