v0.21.0-ember-primitives: Prepare Release using 'release-plan' (#328)

Release (2024-06-28)

ember-primitives 0.21.0 (minor)

🚀 Enhancement

• docs-app, ember-primitives, test-app
  • #336 Support hash-only transitions in proper-links (@mmun)
  • #325 Upgrade form-data-utils (@NullVoxPopuli)

📝 Documentation

• docs-app
  • #331 fix broken links in proper-links.md (@johanrd)

🏠 Internal

• Other
  • #335 Re-roll lock, pin macros (@NullVoxPopuli)
• docs-app, test-app
  • #334 Get app watching working (@NullVoxPopuli)

Committers: 3

• Martin Muñoz (@mmun)
• @NullVoxPopuli
• @johanrd