With the move towards autodetecting available features, there is no reason to keep SmartPlug around.
kasa.smart.SmartPlug is removed in favor of kasa.smart.SmartDevice which offers the same functionality.
Information about auto_off can be accessed using Features of the AutoOffModule on supported devices.
Co-authored-by: Steven B. <51370195+sdb9696@users.noreply.github.com>