Bump FluentAssertions from 6.5.1 to 6.6.0 in /source

Bumps [FluentAssertions](https://github.com/fluentassertions/fluentassertions) from 6.5.1 to 6.6.0.
- [Release notes](https://github.com/fluentassertions/fluentassertions/releases)
- [Changelog](https://github.com/fluentassertions/fluentassertions/blob/develop/AcceptApiChanges.ps1)
- [Commits](fluentassertions/fluentassertions@6.5.1...6.6.0)

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

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

source/Tests/Tests.csproj

@@ -10,7 +10,7 @@
       <PackageReference Include="Serilog" Version="2.10.0" />
       <PackageReference Include="Serilog.Sinks.TextWriter" Version="2.1.0" />
       <PackageReference Include="NSubstitute" Version="4.3.0" />
-      <PackageReference Include="FluentAssertions" Version="6.5.1" />
+      <PackageReference Include="FluentAssertions" Version="6.6.0" />
       <PackageReference Include="NUnit3TestAdapter" Version="4.2.1" />
       <PackageReference Include="TeamCity.VSTest.TestAdapter" Version="1.0.36" />
     </ItemGroup>