Bump Microsoft.WindowsAppSDK from 1.3.230724000 to 1.4.230913002

Bumps [Microsoft.WindowsAppSDK](https://github.com/microsoft/windowsappsdk) from 1.3.230724000 to 1.4.230913002.
- [Release notes](https://github.com/microsoft/windowsappsdk/releases)
- [Commits](https://github.com/microsoft/windowsappsdk/commits)

---
updated-dependencies:
- dependency-name: Microsoft.WindowsAppSDK
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Directory.Packages.props

@@ -32,7 +32,7 @@
     <PackageVersion Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="7.0.0" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.7.1" />
     <PackageVersion Include="Microsoft.Windows.SDK.BuildTools" Version="10.0.22621.756" />
-    <PackageVersion Include="Microsoft.WindowsAppSDK" Version="1.3.230724000" />
+    <PackageVersion Include="Microsoft.WindowsAppSDK" Version="1.4.230913002" />
     <PackageVersion Include="Serilog.Extensions.Hosting" Version="7.0.0" />
     <PackageVersion Include="Serilog.Sinks.Debug" Version="2.0.0" />
     <PackageVersion Include="SpecFlow.Plus.LivingDocPlugin" Version="3.9.57" />