Update dependencies from https://github.com/dotnet/corefx build 20200117.2 (#8984)

- System.Text.Json - 4.7.1
- Microsoft.Private.CoreFx.NETCoreApp - 4.7.0-servicing.20067.2

Author: dotnet-maestro[bot]

NuGet.config

@@ -8,7 +8,7 @@
     <clear />
     <!--Begin: Package sources managed by Dependency Flow automation. Do not edit the sources below.-->
     <add key="darc-pub-dotnet-standard-a5b5f2e" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-standard-a5b5f2e1/nuget/v3/index.json" />
-    <add key="darc-pub-dotnet-corefx-d658fef" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-corefx-d658fef8/nuget/v3/index.json" />
+    <add key="darc-pub-dotnet-corefx-e946ceb-1" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-corefx-e946cebe-1/nuget/v3/index.json" />
     <add key="darc-pub-dotnet-corefx-0f7f38c" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-corefx-0f7f38c4/nuget/v3/index.json" />
     <!--End: Package sources managed by Dependency Flow automation. Do not edit the sources above.-->
     <!--

eng/Version.Details.xml

@@ -4,7 +4,7 @@
     <!-- Keep System.Text.Json at the top of this file while we build 3.1.2 -->
     <Dependency Name="System.Text.Json" Version="4.7.1">
       <Uri>https://github.com/dotnet/corefx</Uri>
-      <Sha>d658fef8c064c2f3ea4f57ab6544abb998ab3b57</Sha>
+      <Sha>e946cebe43a510e8c6476bbc8185d1445df33a1a</Sha>
     </Dependency>
     <Dependency Name="Microsoft.NETCore.Platforms" Version="3.1.0">
       <Uri>https://github.com/dotnet/corefx</Uri>
@@ -14,9 +14,9 @@
       <Uri>https://github.com/dotnet/corefx</Uri>
       <Sha>0f7f38c4fd323b26da10cce95f857f77f0f09b48</Sha>
     </Dependency>
-    <Dependency Name="Microsoft.Private.CoreFx.NETCoreApp" Version="4.7.0-servicing.20066.1">
+    <Dependency Name="Microsoft.Private.CoreFx.NETCoreApp" Version="4.7.0-servicing.20067.2">
       <Uri>https://github.com/dotnet/corefx</Uri>
-      <Sha>d658fef8c064c2f3ea4f57ab6544abb998ab3b57</Sha>
+      <Sha>e946cebe43a510e8c6476bbc8185d1445df33a1a</Sha>
     </Dependency>
     <Dependency Name="Microsoft.Win32.Registry.AccessControl" Version="4.7.0">
       <Uri>https://github.com/dotnet/corefx</Uri>

eng/Versions.props

@@ -56,7 +56,7 @@
     <!-- corefx -->
     <MicrosoftNETCorePlatformsPackageVersion>3.1.0</MicrosoftNETCorePlatformsPackageVersion>
     <MicrosoftNETCoreTargetsPackageVersion>3.1.0</MicrosoftNETCoreTargetsPackageVersion>
-    <MicrosoftPrivateCoreFxNETCoreAppPackageVersion>4.7.0-servicing.20066.1</MicrosoftPrivateCoreFxNETCoreAppPackageVersion>
+    <MicrosoftPrivateCoreFxNETCoreAppPackageVersion>4.7.0-servicing.20067.2</MicrosoftPrivateCoreFxNETCoreAppPackageVersion>
     <MicrosoftWin32RegistryAccessControlVersion>4.7.0</MicrosoftWin32RegistryAccessControlVersion>
     <MicrosoftWin32RegistryVersion>4.7.0</MicrosoftWin32RegistryVersion>
     <MicrosoftWin32SystemEventsVersion>4.7.0</MicrosoftWin32SystemEventsVersion>