Minor update

Author: daxian-dbw

shell/AIShell.Kernel/Utility/Utils.cs

@@ -8,7 +8,6 @@
 using System.Text.Json.Serialization;
 using Microsoft.PowerShell;
 using AIShell.Abstraction;
-using Microsoft.VisualBasic;
 
 namespace AIShell.Kernel;
 

shell/agents/Microsoft.Azure.Agent/Command.cs

@@ -1,6 +1,5 @@
 using System.CommandLine;
 using System.Text;
-using System.Text.Json;
 using AIShell.Abstraction;
 
 namespace Microsoft.Azure.Agent;