Missed ref assembly updates

Author: John Luo

src/DataProtection/DataProtection/ref/Microsoft.AspNetCore.DataProtection.csproj

@@ -1,7 +1,7 @@
 <!-- This file is automatically generated. -->
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netstandard2.0</TargetFrameworks>
+    <TargetFrameworks>netstandard2.0;netcoreapp3.0</TargetFrameworks>
   </PropertyGroup>
   <ItemGroup Condition="'$(TargetFramework)' == 'netstandard2.0'">
     <Compile Include="Microsoft.AspNetCore.DataProtection.netstandard2.0.cs" />
@@ -15,4 +15,15 @@
     <Reference Include="System.Security.Cryptography.Xml"  />
     <Reference Include="System.Security.Principal.Windows"  />
   </ItemGroup>
+<ItemGroup Condition="'$(TargetFramework)' == 'netcoreapp3.0'">
+    <Compile Include="Microsoft.AspNetCore.DataProtection.netcoreapp3.0.cs" />
+    <Reference Include="Microsoft.AspNetCore.Cryptography.Internal"  />
+    <Reference Include="Microsoft.AspNetCore.DataProtection.Abstractions"  />
+    <Reference Include="Microsoft.Extensions.DependencyInjection.Abstractions"  />
+    <Reference Include="Microsoft.Extensions.Hosting.Abstractions"  />
+    <Reference Include="Microsoft.Extensions.Logging.Abstractions"  />
+    <Reference Include="Microsoft.Extensions.Options"  />
+    <Reference Include="Microsoft.Win32.Registry"  />
+    <Reference Include="System.Security.Cryptography.Xml"  />
+  </ItemGroup>
 </Project>