Fix sleep after push message back to queue after resend

What's Changed

• correct the order of pushing and yielding in resending procedure by @sunnyanthony in #137
• Up version 0.6.11 by @Lenka42 in #138

New Contributors

• @sunnyanthony made their first contribution in #137

Full Changelog: v0.6.10...v0.6.11

Fix unsubscribe and heap storage behavior

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

Handle unexpected errors while reconnecting

v0.6.9

Improve tests: Increased the time for waiting of the message;

Fix issue with topics;

v0.6.8

[Fix #118] encode str to bytes;

Handle incoming topic alias in proper way

v0.6.7

Fix #96: Process incoming `topic_alias` in rigth way

Fix python3.8 warning and improve disconnect process

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

Fix subscription identifier

Subscription identifier from the Subscription object has not been used for building package's properties;

Fixed keep alive behaviour

Fixed keep alive behaviour based on last_data_in, last_data_out properties

Changed time periods for keepalive check

Changed time periods for keepalive check (better behaviour on MacOS)

Close connection when lost heartbeat

Close connection when lost heartbeat