Remove .NET Standard 2.1 support

[joachimgoris]

Is your feature request related to a problem? Please describe.
I am wondering why we support .NET Standard 2.1. .NET Standard 2.1 only adds support for Xamarin, Mono and Unity. .NET Framework support is lost due to it being .NET Standard 2.1 instead of 2.0.

Describe the solution you'd like
Remove the support for .NET Standard and only keep supporting .NET versions.

Describe alternatives you've considered
Remove support for .NET standard and add support for .NET Standard 2.0 so it does support .NET Framework.

[stijnmoreels]

Backwards compatibility reasons is the main one. In Arcus.Testing, this already removed, but other Arcus repo's there might indeed some chore work to be done.

[joachimgoris]

So it's okay to remove but hasn't been removed yet?

[stijnmoreels]

So it's okay to remove but hasn't been removed yet?

It needs to be discussed first. Arcus.Testing had the luxuary that it didn't build on top of .NET Standard in the beginning.