Easy. Was looking for a resolution for this earlier and I all I had to do was just add this in the projects affected.
<PropertyGroup>
<RuntimeFrameworkVersion>2.1.1</RuntimeFrameworkVersion>
</PropertyGroup>
Additionally for .NET Core 3 and beyond,
<PropertyGroup>
<TargetFramework>netcoreapp3.1</TargetFramework>
</PropertyGroup>
There was also an answer posted by Patrick below pointing out that certain projects require the .NET Core App NuGet Package. You won’t need that anymore after .NET Core 3.