Update to .NET 6.0
As .NET 6 is an LTS the countdown for 3.1's death started on its release.
After Dec 3, 2022 .NET 3.1 will no longer be supported or patched.
This work is in-progress in #76, but currently blocked by downstream projects. I'm working with downstream projects to figure out a timeline.
@blowdart mentioned there are some people on the dotnet team that could help get those projects up-to-date. I don't think we're at the stage where we need the assistance, but maybe in the near future, depending on what those projects reply.
The blocker our team had internally for this was resolved last week. @JamieMagee will hopefully be taking a look at this change later this week.
Resolved in #288