Also generate arm Docker containers on release

[nemunaire]

Hi! And many thanks for this project!

I use matterircd on arm (v7) servers through Docker.

Until now, I built the image on the host after each matterircd update.
As I just notice you already built containers for arm64 hosts, could you also built Docker images for arm?

[42wim]

Thanks, new releases will now also add arm containers