Updated NuGet.config - replace msbuild feed bb7

Author: vseanreesermsft

NuGet.config

@@ -13,6 +13,7 @@
     <add key="darc-int-dotnet-aspnetcore-cea5fa6" value="https://pkgs.dev.azure.com/dnceng/internal/_packaging/darc-int-dotnet-aspnetcore-cea5fa61/nuget/v3/index.json" />
     <!--  End: Package sources from dotnet-aspnetcore -->
     <!--  Begin: Package sources from DotNet-msbuild-Trusted -->
+    <add key="darc-pub-DotNet-msbuild-Trusted-bb7294f-1" value="https://pkgs.dev.azure.com/dnceng/public/_packaging/darc-pub-DotNet-msbuild-Trusted-bb7294f7-1/nuget/v3/index.json" />
     <!--  End: Package sources from DotNet-msbuild-Trusted -->
     <!--  Begin: Package sources from dotnet-roslyn-analyzers -->
     <!--  End: Package sources from dotnet-roslyn-analyzers -->