Add new 3rd party dependencies to Signing.props to fix official build (#8222)

Author: joperezr

eng/Signing.props

@@ -21,6 +21,9 @@
     <FileSignInfo Include="Grpc.Net.Client.dll" CertificateName="3PartySHA2" />
     <FileSignInfo Include="Grpc.Net.ClientFactory.dll" CertificateName="3PartySHA2" />
     <FileSignInfo Include="Grpc.Net.Common.dll" CertificateName="3PartySHA2" />
+    <FileSignInfo Include="MessagePack.dll" CertificateName="3PartySHA2" />
+    <FileSignInfo Include="MessagePack.Annotations.dll" CertificateName="3PartySHA2" />
+    <FileSignInfo Include="Spectre.Console.dll" CertificateName="3PartySHA2" />
   </ItemGroup>
 
   <ItemGroup>