Support multiple .NET Framework versions

[cjdutoit]

Allow support for both netstandard2.0 and netstandard2.1

This will allow usage in .Net Framework 4.8 which will continue to be distributed with future releases of Windows.

[sunnynagavo]

@cjdutoit, I see already this is supported, may be we can close this issue. I sent a PR to add support for .net 10.0 here #68