Bump FluentAssertions from 6.12.0 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]

Directory.Packages.props

@@ -10,7 +10,7 @@
   -->
   <ItemGroup>
     <PackageVersion Include="coverlet.collector" Version="6.0.2" />
-    <PackageVersion Include="FluentAssertions" Version="6.12.0" />
+    <PackageVersion Include="FluentAssertions" Version="8.8.0" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.9.0" />
     <PackageVersion Include="NUnit" Version="4.1.0" />
     <PackageVersion Include="NUnit3TestAdapter" Version="4.5.0" />