Powershell: DSC tests should be skipped on Ubuntu 20.04, due to libmi incompatibility

[rjmholt]

Testing on Ubuntu 20.04 should skip DSC tests, since Ubuntu 20.04's libmi version isn't compatible.

One of the test errors:

Expected an exception, with FullyQualifiedErrorId 'Microsoft.PowerShell.Commands.WriteErrorException,CheckResourceFound' to be thrown, but the FullyQualifiedErrorId was 'DllNotFoundException,Get-DscResource'. from /opt/microsoft/powershell/7-preview/Modules/PSDesiredStateConfiguration/PSDesiredStateConfiguration.psm1:4681 char:19
+     $resource = @(Get-DscResource @getArguments -ErrorAction stop)
+                   ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Stack trace:

at <ScriptBlock>, /home/vsts_azpcontainer/PSPackage/download/Test/test/powershell/Modules/PSDesiredStateConfiguration/PSDesiredStateConfiguration.Tests.ps1: line 527
527:                 Should -Throw -ErrorId 'Microsoft.PowerShell.Commands.WriteErrorException,CheckResourceFound'

[iSazonov]

/cc @jborean93

[jborean93]

@iSazonov not sure there's much I can add to this, I haven't enabled a Debian 11 target yet because that version isn't out yet. But I would guess that if you tried to include the libmi binary that PowerShell distributes it would fail on Debian 11 because it is compiled against OpenSSL 1.0.2 which newer distros won't ship.