Changes between 5.6.0 and 5.7.0.RC1

This is a pre-release for 5.7.0, a maintenance release with usability improvements and dependency upgrades. All users of the 5.x.x series are encouraged to test this version.

Improve logging for TLS connections

GitHub issue: #441

Don't panic when cancelling an unknown consumer

GitHub issue: #525

Bump dependencies

GitHub issue: #607