2.0.0-rc.2

Enhancements

• Make Task#cancelAll and TaskInstance#cancel awaitable (#396). See
  topic in UPGRADING-2.x.md for more info.

Bugfixes

• Fix TaskProperty extension methods not working with built-in decorators
  (e.g. ember-concurrency-retryable, ember-concurrency-test-waiters, etc.)

Misc.

• [dev] Add test for interop w/ ember-concurrency-decorators
• [dev] Migrate CI to GitHub Actions (#393)