chore(deps): Bump System.Windows.Extensions from 6.0.0 to 8.0.0

Bumps [System.Windows.Extensions](https://github.com/dotnet/runtime) from 6.0.0 to 8.0.0.
- [Release notes](https://github.com/dotnet/runtime/releases)
- [Commits](dotnet/runtime@v6.0.0...v8.0.0)

---
updated-dependencies:
- dependency-name: System.Windows.Extensions
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

PackageViewModel/PackageViewModel.csproj

@@ -1,4 +1,4 @@
-<Project Sdk="Microsoft.NET.Sdk">
+<Project Sdk="Microsoft.NET.Sdk">
 
   <PropertyGroup>
     <TargetFrameworks>netstandard2.1</TargetFrameworks>
@@ -15,7 +15,7 @@
     <PackageReference Include="NuGet.PackageManagement" Version="$(NuGetDependencyVersion)" />    
     <PackageReference Include="NuGet.Commands" Version="$(NuGetDependencyVersion)" />
     <PackageReference Include="NuGet.Resolver" Version="$(NuGetDependencyVersion)" />
-    <PackageReference Include="System.Windows.Extensions" Version="6.0.0" />
+    <PackageReference Include="System.Windows.Extensions" Version="8.0.0" />
     <ProjectReference Include="..\Core\Core.csproj" />
   </ItemGroup>