Update bUnit to preview for .net8.0 release

Author: linkdotnet

tests/Directory.Build.props

@@ -2,7 +2,7 @@
 <Project xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
 
   <ItemGroup Condition="$(MSBuildProjectName) != 'LinkDotNet.Blog.TestUtilities'">
-    <PackageReference Include="bunit" Version="1.21.9" />
+    <PackageReference Include="bunit" Version="1.23.1-preview" />
     <PackageReference Include="FluentAssertions" Version="6.11.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.6.3" />
     <PackageReference Include="Moq" Version="4.18.4" />

tests/LinkDotNet.Blog.IntegrationTests/Web/Features/ShowBlogPost/ShowBlogPostPageTests.cs

@@ -7,6 +7,7 @@
 using LinkDotNet.Blog.Web.Features.Services;
 using LinkDotNet.Blog.Web.Features.ShowBlogPost;
 using LinkDotNet.Blog.Web.Features.ShowBlogPost.Components;
+using Microsoft.AspNetCore.Components.Web;
 using Microsoft.EntityFrameworkCore;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -88,6 +89,7 @@ public async Task ShouldSetStructuredData()
         ctx.JSInterop.Mode = JSRuntimeMode.Loose;
         ctx.AddTestAuthorization();
         RegisterComponents(ctx);
+        ctx.ComponentFactories.AddStub<HeadContent>(ps => ps.Get(p => p.ChildContent));
         var cut = ctx.RenderComponent<ShowBlogPostPage>(
             p => p.Add(b => b.BlogPostId, post.Id));