- Add lib or ref assemblies for the netstandard2.0 target framework

- Add lib or ref assemblies for the net8.0 target framework

- Add lib or ref assemblies for the net48 target framework

Some target frameworks declared in the dependencies group of the nuspec and the lib/ref folder do not have exact matches in the other location. Consult the list of actions below:

-lib/netstandard/_._

-lib/netcoreapp/_._

-lib/net8.0/_._

-lib/net48/_._

This package does not contain a lib/ or ref/ folder, and will therefore be treated as compatible for all frameworks. Since framework specific files were found under the build/ directory for net48, net8.0, netcoreapp, netstandard, consider creating the following empty files to correctly narrow the compatibility of the package: