Bump FluentAssertions from 6.12.1 to 8.8.0

---
updated-dependencies:
- dependency-name: FluentAssertions
  dependency-version: 8.8.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

BlogHelper9000.Tests/BlogHelper9000.Tests.csproj

@@ -12,7 +12,7 @@
         <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
         <PrivateAssets>all</PrivateAssets>
       </PackageReference>
-      <PackageReference Include="FluentAssertions" Version="6.12.1" />
+      <PackageReference Include="FluentAssertions" Version="8.8.0" />
         <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
         <PackageReference Include="NSubstitute" Version="5.1.0" />
         <PackageReference Include="System.IO.Abstractions.TestingHelpers" Version="21.0.29" />