refactor: 移除不使用的命名空间

Author: ArgoZhang

src/BootstrapBlazor.Server/Extensions/CacheManagerExtensions.cs

@@ -4,7 +4,6 @@
 // Maintainer: Argo Zhang([email protected]) Website: https://www.blazor.zone
 
 using Microsoft.Extensions.Caching.Memory;
-using System.Collections.Frozen;
 using System.Globalization;
 
 namespace BootstrapBlazor.Server.Extensions;