MonoGame.Samples/BouncingBox/Core/BouncingBox.Core.csproj

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net8.0</TargetFramework>
    <AssemblyName>BouncingBox.Core</AssemblyName>
    <RootNamespace>Microsoft.Xna.Samples.BouncingBox</RootNamespace>
    <Nullable>enable</Nullable>
  </PropertyGroup>
  <ItemGroup>
    <PackageReference Include="MonoGame.Framework.DesktopGL" Version="3.8.*" />
  </ItemGroup>
</Project>