shpc uninstall fails with docker/podman

[marcodelapierre]

$ shpc uninstall biocontainers/samtools:v1.9-4-deb_cv1
Multiple tags found for biocontainers/samtools/v1.9-4-deb_cv1: 99-shpc.sh, module.lua.

[vsoch]

okay I'll have fixes in for this after work today - also will add uninstall to tests.