refactor: 修复值不稳定问题

Author: ArgoZhang

src/BootstrapBlazor/Components/Checkbox/CheckboxListGeneric.razor.cs

@@ -187,22 +187,7 @@ private async Task<bool> OnBeforeStateChanged(CheckboxState state)
     private async Task OnStateChanged(SelectedItem<TValue> item, bool v)
     {
         item.Active = v;
-        var items = new List<TValue>();
-        if (Value != null)
-        {
-            items.AddRange(Value);
-        }
-
-        var val = items.Find(i => Equals(item.Value, i));
-        if (v && val == null)
-        {
-            items.Add(item.Value);
-        }
-        else
-        {
-            items.Remove(val!);
-        }
-
+        var items = Items.Where(i => i.Active).Select(i => i.Value).ToList();
         CurrentValue = items;
 
         if (OnSelectedChanged != null)