Add dotnet-templating feed to fix build failure

Author: Jason Zhai

NuGet.config

@@ -38,6 +38,7 @@
     <add key="darc-int-dotnet-runtime-831d23e" value="https://pkgs.dev.azure.com/dnceng/internal/_packaging/darc-int-dotnet-runtime-831d23e5/nuget/v3/index.json" />
     <!--  End: Package sources from dotnet-runtime -->
     <!--  Begin: Package sources from dotnet-templating -->
+    <add key="darc-pub-dotnet-templating-693a4fd" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-templating-693a4fd2/nuget/v3/index.json" />
     <add key="darc-pub-dotnet-templating-5936acf" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-dotnet-templating-5936acfc/nuget/v3/index.json" />
     <!--  End: Package sources from dotnet-templating -->
     <!--  Begin: Package sources from dotnet-windowsdesktop -->