Use Podman to build the container image on windows / macOS

[almet]

During the latest release (v0.8.0), we ended up using Podman Desktop rather than Docker Desktop to produce our container image, as Docker was producing images that we weren't able to load in some specific environments.

As a result, it might be beneficial to change our "build backend" in our release instructions and build instructions.

Because we probably don't want to end up in a situation where developers need to install both Docker and Podman, we might want to solve #925 before doing the jump here.