Issue a warning on PowerShell 6 end-of-life for PowerShell 6 apps

[AnatoliB]

From https://docs.microsoft.com/powershell/scripting/powershell-support-lifecycle?view=powershell-7#powershell-releases-end-of-life:

Version	End-of-life
6.2	September 4, 2020

[fabiocav]

@AnatoliB should the milestone here be updated?

[AnatoliB]

@AnatoliB should the milestone here be updated?

@fabiocav Thank you, done