NET Version reports as '.NET vnull'

[hotchkj]

Our reports are showing as reported platform version .NET vnull

Requested Info	Value
Tested library version	v0.8.0.362
Runtime	NET Framework 4.8
Assembly target	NET Standard 2.0

The current NET Standard 2.0 code is looking for a custom attribute

lightstep-tracer-csharp/src/LightStep/Options.cs

Line 239 in bfd0bb8

return Assembly.GetEntryAssembly()?.GetCustomAttribute<TargetFrameworkAttribute>()?.FrameworkName;

According to Microsoft, the recommended way in NET Standard 2.0 to get the platform is RuntimeInformation.FrameworkDescription

If I override the tag:

.WithTags(new Dictionary<string, object>
{
	{LightStepConstants.ComponentNameKey, "mycomponent"},
	{LightStepConstants.TracerPlatformVersionKey, RuntimeInformation.FrameworkDescription}
});

I get reported .NET v.NET Framework 4.8.4200.0. It may be beneficial to adjust the version reporting to drop the .NET v prefix for this case as it appears MS do this for you in this case.