Bump FluentAssertions from 6.11.0 to 6.12.0 (#221)

Bumps [FluentAssertions](https://github.com/fluentassertions/fluentassertions) from 6.11.0 to 6.12.0.
- [Release notes](https://github.com/fluentassertions/fluentassertions/releases)
- [Changelog](https://github.com/fluentassertions/fluentassertions/blob/develop/AcceptApiChanges.ps1)
- [Commits](fluentassertions/fluentassertions@6.11.0...6.12.0)

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

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

Author: dependabot[bot]

src/Directory.Packages.props

@@ -14,7 +14,7 @@
   <!-- Test dependencies -->
   <ItemGroup>
     <PackageVersion Include="Akka.Hosting.TestKit" Version="$(AkkaVersion)" />
-    <PackageVersion Include="FluentAssertions" Version="6.11.0" />
+    <PackageVersion Include="FluentAssertions" Version="6.12.0" />
     <PackageVersion Include="Microsoft.NET.Test.Sdk" Version="17.7.2" />
     <PackageVersion Include="xunit" Version="2.5.1" />
     <PackageVersion Include="xunit.runner.visualstudio" Version="2.5.1" />