Same-day hotfix on 2.0.0, nothing user-facing. It exists because the 2.0.0
archive was built before the MessagePack lift, and because the fixed release
workflow needs a tag to prove itself on -- 2.0.0 cannot, since Gitea reads the
workflow from the tagged tree and that tree still holds the broken version.
Not force-moving the 2.0.0 tag: its release object exists with the archive
attached, and someone may already have pulled it.
