* Add support for C# 12
* Run all tests on all major .NET SDKs
* Only build on Ubuntu
* Do not build docs for pull requests
* Add Cédric Luthi, and Frank Ray to authors
* Drop netstandard2.0 for ImageSharp plugin
Probably something that only bothers me, but I'm in a habit of running dotnet test at the solution level. It was discovering this project as a test project even though it isn't. This produces an error complaining about not having a testhost.dll. I'm pretty sure this comes in via a props when xunit is referenced.
This attribute in the csproj marks the project explicitly as not a test project