Bump FluentAssertions from 8.6.0 to 8.9.0 (#1735)

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

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Author: dependabot[bot]

Directory.Packages.props

@@ -4,7 +4,7 @@
   </PropertyGroup>
   <ItemGroup>
     <PackageVersion Include="BouncyCastle.Cryptography" Version="2.6.2" />
-    <PackageVersion Include="FluentAssertions" Version="8.6.0" />
+    <PackageVersion Include="FluentAssertions" Version="8.9.0" />
     <PackageVersion Include="Fractions" Version="7.3.0" />
     <PackageVersion Include="JsonPatch.Net" Version="3.3.0" />
     <PackageVersion Include="MartinCostello.Logging.XUnit" Version="0.6.0" />