whuppi/ci 2.0.4

• Fixed --stamp-changelog crashing on a package's first-ever release.
  get_published_versions piped pub.dev's response straight into jq; for a
  never-published package pub.dev returns 404 with an XML body, jq exits 5,
  and pipefail killed the publish job (device_io's first publish). A 404 now
  means "zero published versions" — the legitimate first-release state —
  while any other non-200 still fails loudly, since treating pub.dev
  downtime as "nothing published" would misfile real published versions
  under the unpublished collapsible.

Commits since v2.0.3 (2)

• af86170 release: v2.0.4
• fb97482 fix: stamp-changelog no longer crashes on a first-ever publish (#25)