Looks like the latest version of Microsoft.SemanticKernel.Planners.Core (1.0.0-beta8) is not compatible with the latest version of Microsoft.SemanticKernel(1.0.1). The StepWisePlanner`s constructor expects IKernel but there is no IKernel defined in the package. Looks like it was removed. The new constructor expects Kernel type. When the new Microsoft.SemanticKernel.Planners.Core package will be released?
The StepWisePlanner is replaced with FunctionCallingStepwisePlanner. https://devblogs.microsoft.com/semantic-kernel/migrating-from-the-sequential-and-stepwise-planners-to-the-new-handlebars-and-stepwise-planner/
It is working fine after replacing with FunctionCallingStepwisePlanner