revert itemgroup

Author: sungam3r

src/GraphQL.Client/GraphQL.Client.csproj

@@ -15,6 +15,10 @@
     <DefineConstants>NETFRAMEWORK</DefineConstants>
   </PropertyGroup>
 
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.0" PrivateAssets="All" />
+  </ItemGroup>
+  
   <ItemGroup Condition=" '$(TargetFramework)' == 'net461'">
     <PackageReference Include="System.Net.WebSockets.Client.Managed" Version="1.0.22" />
   </ItemGroup>