[Libguestfs] [PATCH nbdkit] ci: Expire artifacts after 1 week

nbdkit uses about 1.1G of storage for artifacts. I have personally never looked at anything other than the artifacts of the latest failed job, so I don't believe we need to keep these around for long. This commit proposes expiring (and thus deleting) artifacts after 1 week. https://gitlab.com/nbdkit/nbdkit/-/usage_quotas If accepted I will make a similar change for libnbd. Martin, Dan - I don't know a lot about this and I know you've looked into this area a lot more. What do you think of this change? Rich.