https://github.com/eventlet/eventlet/issues/940

Summary:
* [fix] Make sure asyncio hub doesn't use greendns for asyncio DNS APIs https://github.com/eventlet/eventlet/pull/938
* [fix] Make asyncio.to_thread work with the same semantics as normal asyncio https://github.com/eventlet/eventlet/pull/930
* [fix] Refactor congruence checks based on assert at runtime https://github.com/eventlet/eventlet/pull/932
* [tests] Run tests on macOS in CI, and some fixes to get it in reasonable state (#list https://github.com/eventlet/eventlet/pull/934
* [fix] Fix wsgi.server shutdown for in-flight requests https://github.com/eventlet/eventlet/pull/912
* [feature] Add debug convenience helpers - asyncio, threads https://github.com/eventlet/eventlet/pull/925
* [fix] Handle errors better. https://github.com/eventlet/eventlet/pull/923