refactor: 精简代码

Author: ArgoZhang

src/BootstrapBlazor/Components/Button/LinkButton.cs

@@ -5,7 +5,6 @@
 
 using Microsoft.AspNetCore.Components.Rendering;
 using Microsoft.AspNetCore.Components.Web;
-using System;
 
 namespace BootstrapBlazor.Components;