Gmqtt

What's Changed
* correct the order of pushing and yielding in resending procedure by sunnyanthony in https://github.com/wialon/gmqtt/pull/137
* Up version 0.6.11 by Lenka42 in https://github.com/wialon/gmqtt/pull/138

New Contributors
* sunnyanthony made their first contribution in https://github.com/wialon/gmqtt/pull/137

**Full Changelog**: https://github.com/wialon/gmqtt/compare/v0.6.10...v0.6.11

* Fair waiting for the heap based storage is empty
* Fix unsubscribe cleans subscriptions storage
* Fix tests

Removed loop attribute when creating an Event object. Wait for disconnect in proper way;