Bump FluentAssertions from 6.12.0 to 6.12.1

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>

tests/DendroDocs.Tool.Tests/DendroDocs.Tool.Tests.csproj

@@ -21,7 +21,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="FluentAssertions" Version="6.12.0" />
+    <PackageReference Include="FluentAssertions" Version="6.12.1" />
     <PackageReference Include="coverlet.collector" Version="6.0.2" PrivateAssets="all">
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
     </PackageReference>