Remove unused package

Author: RehanSaeed

Benchmarks/Boxed.Mapping.Benchmark/Boxed.Mapping.Benchmark.csproj

@@ -13,8 +13,6 @@
   <ItemGroup Label="Package References">
     <PackageReference Include="AutoMapper" Version="12.0.0" />
     <PackageReference Include="BenchmarkDotNet" Version="0.13.2" />
-    <!-- See https://github.com/Microsoft/dotnet/tree/master/releases/reference-assemblies -->
-    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" PrivateAssets="All" Version="1.0.3" />
   </ItemGroup>
 
 </Project>