PowerShell 5 support broken

[indented-automation]

PowerShell 5.1 on Windows 10. PSGitHub 0.15.179

The module uses the FollowRelLink of Invoke-WebRequest / Invoke-RestMethod. This does not exist prior to PowerShell 6.

Should you wish to retain support for PS 5, I wrote an implementation of this as an example. You can find that here:

https://github.com/PacktPublishing/Mastering-Windows-PowerShell-Scripting-Third-Edition/blob/25406afc2395e0e5d68e3f26219a4f42b098baa6/Chapter13/2.2.4_Invoke-WebRequest_FollowRelLink.ps1

Thanks!

[felixfbecker]

Looks good, wanna do a PR?