removed "NuGet.Packaging.Core" from sdk packages list.

Author: kartheekp-ms

NuGetReleaseTool/NuGetReleaseTool/Constants.cs

@@ -24,7 +24,6 @@ public static class Constants
             "NuGet.LibraryModel",
             "NuGet.Localization",
             "NuGet.PackageManagement",
-            "NuGet.Packaging.Core",
             "NuGet.Packaging",
             "NuGet.ProjectModel",
             "NuGet.Protocol",