Improve docker testing recommendations

[corneliusroemer]

Rather than asking to download an artefact manually and feed it into docke for conda install, we could recommend the following to test packages:

DOCKER_DEFAULT_PLATFORM=linux/aarch64 docker run -i -t mambaorg/micromamba /bin/bash -c "\
    micromamba install -yn base -c bioconda -c conda-forge -c https://output.circle-artifacts.com/output/job/d713a33c-7553-45c7-8d9c-158a5fcec50c/artifacts/0/tmp/artifacts/packages auspice==2.52.0  -y && bash"

One can switch the platform between arm64 and amd64 through default platform.

@martin-g any thoughts? The current instructions seem a bit cumbersome: gzip -dc LinuxArtifacts/images/auspice:2.52.0--h03c9045_1.tar.gz \| docker load and don't test whether all the dependencies are available etc.