Revert WindowsSdkPackageVersion to 10.0.22621.37-preview for WindowsAppSDK 1.6 Preview1

Author: Arlodotexe

MultiTarget/WinUI.Extra.props

@@ -33,7 +33,7 @@
 
     <RuntimeIdentifiers Condition="$([MSBuild]::GetTargetFrameworkVersion('$(TargetFramework)')) >= 8">win-x86;win-x64;win-arm64</RuntimeIdentifiers> 
     <RuntimeIdentifiers Condition="8 > $([MSBuild]::GetTargetFrameworkVersion('$(TargetFramework)'))">win10-x86;win10-x64;win10-arm64</RuntimeIdentifiers>
-    <WindowsSdkPackageVersion>10.0.22621.38</WindowsSdkPackageVersion>
+    <WindowsSdkPackageVersion>10.0.22621.37-preview</WindowsSdkPackageVersion>
   </PropertyGroup>
 
   <PropertyGroup Condition="'$(IsUno)' == 'true'">