Support ARM64 architecture

[akrush24]

I would really like to run Alerta on a Raspberry Pi or on Apple Silicon processors.

Please support ARM architecture.

[akrush24]

I built a Docker image for the arm64 architecture. If anyone finds it useful, you can take it from here: https://registry.hub.docker.com/repository/docker/akrush/alerta-web/tags.

However, I would like it to be included in the official distribution.
Thanks!

[sharmakhimlal]

Could you please provide Dockerfile for this, I want to use this on my k3s cluster.