remove nuget package refs no longer required after move to net5.0
CommandDotNet.Spectre.Testing targets net5.0 instead of netstandard2.0. This will allow us to take advantage of new framework features. We're holding off on net6.0 at the moment because it's new enough many companies will not be able to adopt it yet.
AnsiTestConsole updated in response to changes in IConsole and TestConsole
Test support for IAnsiConsole
Read more about it here