Target netstandard2.1

[michaelklishin]

In main it feels appropriate to target a supported modern LTS version of .NET.

Per discussion with @Zerpet.

[bording]

This is not a good idea. netstandard2.1 is a dead end that is only support by .NET Core 3.1 and newer.

.NET Core 3.1 is already out of support, so you're already targeting net6.0, which is the oldest support .NET version.

Another thing to consider here is the idea of removing support for .NET Framework, which is another thing this PR is doing. This is going to be controversial, and might be too aggressive.

[lukebakken]

We can't make the changes in this PR. Check out this long discussion - #1189

@michaelklishin @Zerpet we should be able to use conditionals in the .csproj files to make things more OS X friendly.

[michaelklishin]

@bording interesting, I have seen a page on one of Microsoft sites that lists netstandard2.1 as supported by .NET 6.0.

[bording]

@bording interesting, I have seen a page on one of Microsoft sites that lists netstandard2.1 as supported by .NET 6.0.

It is, but there just isn't a point to targeting it. Not enough things support it, so you're better off just targeting net6.0 directly at this point.

[stebet]

I agree with @bording. Just target 'net6.0'.