Use pester 4.0 syntax to the install tests (#2713)
Use pester 4.0 syntax to the install tests (#2713)

This PR updates the `should` Pester calls with the 4.0 syntax in the `Scoop-Install.Tests.ps1` file
lukesampson/scoop,nikolasd/scoop,berwyn/scoop,coonce/scoop,rasa/scoop,kodybrown/scoop