kn 0.23.0 comes with bug fixes and API updates only.
Meta
The compile dependencies have been updated to Knative Serving 0.23.0 and Knative Eventing 0.23.0. There are no changes in the used API version for communicating with the backend. Eventing Sources APIServerSource, ContainerSource and SinkBinding are now accessed with their v1 API version (which implies, that you can manage those sources only for Knative installations that offer these sources in a v1 version, for older clusters you need to use kn <= 0.22). PingSource API access has been updated to v1beta2.
You can find the complete list of changes in the CHANGELOG