v0.8.21

Changelog

• 8cce1bc: Update version numbers: 0.8.20 (@dev-errant)
• ad3f96e: dctr: adjust how CLI is loaded (#304) (@nicks)
• fc87b38: docker: pass credentials to image pull (#306) (@nicks)
• 099d599: go: update to 1.21 (#305) (@nicks)
• 96f78bc: goreleaser: fix some deprecations (#297) (@nicks)
• 7b17159: vendor: upgrade to docker v24 (#302) (@nicks)