chore(deps): bump Microsoft.UI.Xaml from 2.7.1 to 2.8.5

Bumps [Microsoft.UI.Xaml](https://github.com/microsoft/microsoft-ui-xaml) from 2.7.1 to 2.8.5.
- [Release notes](https://github.com/microsoft/microsoft-ui-xaml/releases)
- [Commits](microsoft/microsoft-ui-xaml@v2.7.1...v2.8.5)

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

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

Uno.Gallery/Uno.Gallery.UWP/Uno.Gallery.UWP.csproj

@@ -1,4 +1,4 @@
-<?xml version="1.0" encoding="utf-8"?>
+<?xml version="1.0" encoding="utf-8"?>
 <Project ToolsVersion="15.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
   <ItemGroup>
@@ -19,7 +19,7 @@
       <Version>6.1.0</Version>
     </PackageReference>
     <PackageReference Include="Microsoft.UI.Xaml">
-      <Version>2.7.1</Version>
+      <Version>2.8.5</Version>
     </PackageReference>
     <PackageReference Include="nventive.Nimue.Application.Packaging">
       <Version>0.1.0-alpha.58</Version>