(FEEDBACK WANTED): Support .NET 8 and .NET Standard 2.0

@mega5800 I was contacted by a lessmsi user who has migrated lessmsi to [.NET 8](https://learn.microsoft.com/en-us/dotnet/core/whats-new/dotnet-8/overview) and [.NET Standard 2.0](https://learn.microsoft.com/en-us/dotnet/standard/net-standard?tabs=net-standard-2-0) (maybe also see https://learn.microsoft.com/en-us/dotnet/standard/library-guidance/cross-platform-targeting) and provided me access to his code changes. I think this is valuable to contributors if we just keep lessmsi using the latest platform libraries, but honestly I'm not very confident.

Do you think it's valuable to users and/or contributors if we migrate lessmsi to .NET 8 and .NET Standard 2.0?

Would it still work on the operating systems we support according to the [Supported Windows Versions section of the README](https://github.com/activescott/lessmsi#supported-windows-versions)?

If so, are you interested in contributing it? Happy to provide you access to his code (and he also said that would be fine).