MacOS Powershell not supported

[planetscripton]

1. Provide a general summary of the issue in the Title above

2. Describe Your Environment

Operating System and PowerShell version:
MacOS 10.13.3, PowerShell 6.0.1

3. Expected Behavior

[comment] If you're describing a bug, tell us what should happen
[comment] If you're suggesting a change/improvement, tell us how it should work

MacOS should be supported when running Save-GitlabApiConfiguration

4.Current Behavior

[comment] If describing a bug, tell us what happens instead of the expected behavior
[comment] If suggesting a change/improvement, explain the difference from current behavior

Currently checks for $IsLinux and $IsWindows, but not $IsMacOS. Gives unknown platform error for MacOS.

5. Possible Solution

[comment] Have a solution in mind?

6. Context

[Comment] How has this issue affected you? What are you trying to accomplish?
Trying to use PowerShell for MacOS for all my gitlab management.

[ngetchell]

I'll have to steal my wife's Macbook Air for the night and see what I can fix.

[planetscripton]

Look forward to being able to use this on mac :)