Update Microsoft.WindowsAppSDK to 1.6.240807006-preview1, remove CsWinRT1028 suppression.

Author: Arlodotexe

Directory.Build.props

@@ -12,16 +12,7 @@
   <PropertyGroup Condition=" '$(Configuration)' == 'Release' ">
     <EnforceCodeStyleInBuild>true</EnforceCodeStyleInBuild>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
-    <NoWarn>$(NoWarn);Uno0001</NoWarn>
-    <!--
-      Suppress 'error CsWinRT1028: Class implements WinRT interfaces but isn't marked partial. ' for generated XamlMetaDataProvider.g.cs.
-      Fix is expected to arrive in prerelease1 of Microsoft.WindowsAppSdk 1.6.
-      Internal tracking: https://microsoft.visualstudio.com/OS/_workitems/edit/52541822/
-
-      Notice: This suppression affects CsWinRT1028 for all generated and non-generated code.
-        Disable to check non-generated code for CsWinRT1028.
-     -->
-    <NoWarn>$(NoWarn);CsWinRT1028;</NoWarn>    
+    <NoWarn>$(NoWarn);Uno0001</NoWarn> 
   </PropertyGroup>
 
   <Import Project="Windows.Toolkit.Common.props" />