Update IconButton.axaml

修正 IconButton 在设置 IsLoading 后，CPU 占用异常的问题。

src/Ursa.Themes.Semi/Controls/IconButton.axaml

@@ -72,6 +72,7 @@
                             <u:LoadingIcon
                                 Classes="Small"
                                 Foreground="{TemplateBinding Foreground}"
+                                IsLoading="{TemplateBinding IsLoading}"
                                 IsVisible="{TemplateBinding IsLoading}" />
                         </Panel>
                         <ContentPresenter
@@ -304,4 +305,4 @@
             <Setter Property="Foreground" Value="{DynamicResource ButtonDefaultDisabledForeground}" />
         </Style>
     </ControlTheme>
-</ResourceDictionary>
+</ResourceDictionary>