[CI] Update SignList.xml to fix publishing

dotnet/Workloads/SignList.xml

@@ -5,6 +5,7 @@
     <!-- Microsoft.iOS.Windows.Sdk content -->
     <Skip Include="tools\msbuild\iOS\Microsoft.Win32.Registry.dll" />
     <Skip Include="tools\msbuild\iOS\System.Buffers.dll" />
+    <Skip Include="tools\msbuild\iOS\System.Formats.Asn1.dll" />
     <Skip Include="tools\msbuild\iOS\System.Memory.dll" />
     <Skip Include="tools\msbuild\iOS\System.Numerics.Vectors.dll" />
     <Skip Include="tools\msbuild\iOS\System.Runtime.CompilerServices.Unsafe.dll" />