v4.0.x: AMQP 1.0 .NET-based integration suite: an attempt to fix 'dotnet restore'

[michaelklishin]

As a result recent Actions environment upgrade, dotnet restore currently throws

Process terminated. Couldn't find a valid ICU package installed on the system.
Set the configuration flag System.Globalization.Invariant to true if you want
to run with no globalization support.

on v4.0.x.

[michaelklishin]

Per discussion with @ansd: perhaps an even better idea would be to upgrade .NET to 8 in v4.0.x, there is no reason why it should stay on 3.1.x :)