Run net472 unit tests on CI · riganti/dotvvm@6dfcb07

The target framework 'net5.0' is out of support and will not receive security updates in the future. Please refer to https://aka.ms/dotnet-core-support for more information about the support policy.

Detected Razor language version downgrade. This is typically caused by a reference to the Microsoft.AspNetCore.Razor.Design package. Consider removing this package reference.