build(deps): bump FluentAssertions from 6.12.0 to 6.12.1 (#10202)

Bumps [FluentAssertions](https://github.com/fluentassertions/fluentassertions) from 6.12.0 to 6.12.1.
- [Release notes](https://github.com/fluentassertions/fluentassertions/releases)
- [Changelog](https://github.com/fluentassertions/fluentassertions/blob/develop/AcceptApiChanges.ps1)
- [Commits](fluentassertions/fluentassertions@6.12.0...6.12.1)

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

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

Directory.Packages.props

@@ -56,7 +56,7 @@
   <ItemGroup>
     <!-- Test only -->
     <PackageVersion Include="coverlet.collector" Version="6.0.2" />
-    <PackageVersion Include="FluentAssertions" Version="6.12.0" />
+    <PackageVersion Include="FluentAssertions" Version="6.12.1" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.11.1" />
     <PackageVersion Include="PublicApiGenerator" Version="11.1.0" />
     <PackageVersion Include="Verify.DiffPlex" Version="3.1.0" />