refactor: breaking change to remove sync APIs

[allenporter]

Two breaking changes:

• Remove the sync APIs. Callers need to update from the sync_ version to the fully async_ version. These APIs currenty log warnings when not called from an async when an event loop is not started.
• These APIs will now log when the client library is not shutdown properly. The caller must call the async release methods when shutting down to free any resources rather than relying on the __del__ method which is not async. This is logged at debug since i'm not sure how reliable it is to check "is_connected"

Issue #228