Update links on https://snapcraft.io/concierge

Tool has moved from jnsgruk to canoical, yet the links remain

Release seems to be done via https://github.com/canonical/concierge/blob/a0dda2dc0ec54373f16afac243ea716201878960/.goreleaser.yaml#L28-L57

That doesn't reference jnsgruk, so I'm not sure where the source of truth is.

Open the links on https://snapcraft.io/concierge and inspect .goreleaser.yaml around lines 28-57 to understand the current release references. Identify the remaining jnsgruk links, update them to the canonical locations, and verify that the page no longer points to the old owner.

Written by the indexing model from the issue text.