Targeting netstandard2.0 and net6.0 should be enough for the library as that should support all currently supported verions of .Net Framework (4.6.2+) and .NET (6.0+) while allowing it to compile on linux.
(Technically .NET Framework 3.5 Service Pack 1 is still supported but we
currently don't support that anyway)
For the test projects I just went with the latest .NET version as .NET 5.0 isn't supported anymore.
Targeting netstandard2.0 and net6.0 should be enough for the library as that should support all currently supported verions of .Net Framework (4.6.2+) and .NET (6.0+) while allowing it to compile on linux.
(Technically .NET Framework 3.5 Service Pack 1 is still supported but we currently don't support that anyway)
For the test projects I just went with the latest .NET version as .NET 5.0 isn't supported anymore.