build(deps): bump Microsoft.WindowsAppSDK from 1.3.230724000 to 1.4.230913002 in /src (#3617)

Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

src/ReactiveUI.WinUI/ReactiveUI.WinUI.csproj

@@ -10,7 +10,7 @@
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="Microsoft.WindowsAppSDK" Version="1.3.230724000" />
+    <PackageReference Include="Microsoft.WindowsAppSDK" Version="1.4.230913002" />
   </ItemGroup>
 
   <ItemGroup>