Release 3.1.0 - this is 3.0.x updated to use Roslyn 2.10, thus bringing full C# 7.3 support for Umbraco 7.
However
Running Roslyn 2.10 with .NET Framework prior to 4.7.2 (the one we use for v8) is particularly painful. You will have to update some binding redirects in your web.config file for it to work, and which binding redirects... depend on each situation, so we cannot provide an easy upgrade path. And it might not work at all. And we cannot support it.
This version will not be uploaded to NuGet, to prevent people from auto-upgrading by accident.
Upgrade if you understand the risks.