chore: Bump FluentAssertions from 8.3.0 to 8.8.0

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

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

Author: dependabot[bot]

Directory.Packages.props

@@ -10,7 +10,7 @@
     <PackageVersion Include="ModelContextProtocol" Version="0.2.0-preview.3" />
     <!-- Testing packages -->
     <PackageVersion Include="Moq" Version="4.20.72" />
-    <PackageVersion Include="FluentAssertions" Version="8.3.0" />
+    <PackageVersion Include="FluentAssertions" Version="8.8.0" />
     <PackageVersion Include="coverlet.collector" Version="6.0.4" />
     <PackageVersion Include="Microsoft.Extensions.DependencyInjection" Version="9.0.6" />
     <PackageVersion Include="Microsoft.Extensions.Hosting" Version="9.0.6" />