ListNode<T>.WithNodes covariant return type

[0.13.0] - 2021-09-16

Changed

• ListNode<T>-derived classes (e.g. ItemListNode) now have covariant return with self type
  in WithNodes method override (e.g. ItemListNode ItemListNode.WithNodes(nodes)). (#133)
• wham publish fixed to work on repositories with no gst file. (#135)