fix: i18n use en_US.axaml as default language resource

Author: gadfly3173

src/Resources/Locales/zh_CN.axaml

@@ -1,4 +1,7 @@
 <ResourceDictionary xmlns="https://github.com/avaloniaui" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+  <ResourceDictionary.MergedDictionaries>
+    <ResourceInclude Source="en_US.axaml"/>
+  </ResourceDictionary.MergedDictionaries>
   <x:String x:Key="Text.About" xml:space="preserve">关于软件</x:String>
   <x:String x:Key="Text.About.Menu" xml:space="preserve">关于本软件</x:String>
   <x:String x:Key="Text.About.BuildWith" xml:space="preserve">• 项目依赖于 </x:String>