Installing module Pester fails in Windows Server 2016 AppVeyor build worker

[johlju]

When using a AppVeyor build worker with Windows Server 2016 then Pester must be installed using the parameter -SkipPublisherCheck.

PackageManagement\Install-Package : The version '4.0.5' of the module 'Pester' being installed is not catalog signed. Ensure that the version '4.0.5' of the module 'Pester' has the catalog file 'Pester.cat' and signed with the 
same publisher 'CN=Microsoft Root Certificate Authority 2010, O=Microsoft Corporation, L=Redmond, S=Washington, C=US' as the previously-installed module '4.0.5' with version '3.4.0' under the directory 'C:\Program 
Files\WindowsPowerShell\Modules\Pester\3.4.0'. If you still want to install or update, use -SkipPublisherCheck parameter.
At C:\Program Files\WindowsPowerShell\Modules\PowerShellGet\1.0.0.1\PSModule.psm1:1772 char:21
+ ...          $null = PackageManagement\Install-Package @PSBoundParameters
+                      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    + CategoryInfo          : InvalidOperation: (Microsoft.Power....InstallPackage:InstallPackage) [Install-Package], Exception
    + FullyQualifiedErrorId : ModuleIsNotCatalogSigned,Validate-ModuleAuthenticodeSignature,Microsoft.PowerShell.PackageManagement.Cmdlets.InstallPackage