Azure Function App Build Error - Multiple Assemblies with Equivalent

I have not touched my Azure functions in several months. I came back yesterday and made changes which I then pushed to Github. The CI integration failed to build my changes however, because of the error below:

```
CSC : error CS1703: Multiple assemblies with equivalent identity have been imported:
'D:\home\site\repository\packages\System.Xml.ReaderWriter.4.3.0\lib\net46\System.Xml.ReaderWriter.dll'
and
'D:\Program Files (x86)\Reference Assemblies\Microsoft\Framework\.NETFramework\v4.6.1\Facades\System.Xml.ReaderWriter.dll'.
Remove one of the duplicate references. [D:\home\site\repository\DataModel\DataModel.csproj
```

It seems like maybe this library now exists on the server by default now, so there's a conflict when it tries to load it again via Nuget. The problem is, we obviously still need to reference the Nuget package in the project for our development machines to download it.

However, if this were the case, it seems like it would be a very common scenario but I found no other reports of this in the context of Azure Functions. So, I'm wondering if it's related to a recent change, or if it seems to be a unique situation in my code or function app.