Bump FluentAssertions from 8.2.0 to 8.9.0 (#539)

---
updated-dependencies:
- dependency-name: FluentAssertions
  dependency-version: 8.9.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] 
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

tests/Directory.Build.props

@@ -31,7 +31,7 @@
 
   <ItemGroup>
     <PackageReference Include="AutoFixture" Version="4.18.1" />
-    <PackageReference Include="FluentAssertions" Version="8.2.0" />
+    <PackageReference Include="FluentAssertions" Version="8.9.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
     <PackageReference Include="Moq" Version="4.20.72" />
     <PackageReference Include="MSTest.TestAdapter" Version="3.8.3" />