We use precompiled pages for ASP.NET MVC on our site. Recently I tried to upgrade the StackifyLib nuget project from 2.1.0 to 2.1.3. When I did that I started getting an error during publish:

aspnet_merge(0,0): Error occurred: An error occurred when merging assemblies: Unresolved assembly reference not allowed: System.Net.Http.

This also occurs if I upgrade to StackifyLib 2.1.2.

We are targeting .NET 4.7.2. We have the following installed:
StackifyHttpModule version="1.0.28.0"
StackifyLib" version="2.1.0"
StackifyLib.log4net" version="2.1.0"