multi-arch docker images

[thomas-brx]

While looking at moving our workloads across to ARM instances, we noticed that snowplow-s3-loader is only built for limux/amd64.

Other parts of the pipeline, for example the enricher, do have arm64 images built, would be great to see this for the s3 loader as well.

[sqlheisenberg]

+1 for this. Thanks Thomas Broquist (@thomas-brx) for reporting, i hope maintainers will take a look into this soon.