v0.21.1

What's Changed

• fix(shorebird_cli): don't copy directory before zipping by @bryanoltman in #1612
• chore: track pubspec.lock files by @bryanoltman in #1613
• chore: draft release 0.21.1 by @bryanoltman in #1614

Full Changelog: v0.21.0...v0.21.1