MonoGame.Samples/Primitives/Core/Primitives.Core.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <AssemblyName>Primitives.Core</AssemblyName>
    <RootNamespace>PrimitivesSample.Core</RootNamespace>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="MonoGame.Framework.DesktopGL" Version="3.8.*" />
  </ItemGroup>
</Project>