Generated and skill bots should work with .Net 8.0

[JhontSouth]

Is your feature request related to a problem? Please describe.

Current generated and skill bots are pinned to be used with .Net 6.0 and can't be built with .Net 8.0

Describe the solution you'd like

Update the generator and skill bots pinned version to work with .Net 8.0.

Additional context

The bots can be updated to .Net 8.0, but the templates and default versions used here should be working with the .Net latest versions.