Add support for .net 4.72, 4.71

[TakeitEasyAlan]

User story

As a developer, I want to add helix projects with the .net framework 4.72, 4.71 so that I can create projects that target either 4.72 or 4.71

Expected behavior

Can select 4.72, 4.71

Actual behavior

Can only select up to 4.7.0

Steps to reproduce the behavior

Use helix:add, and see that 4.72, 4.71 are not in the list of target frameworks