build(deps): bump FluentAssertions from 6.7.0 to 6.12.0 in /src

Bumps [FluentAssertions](https://github.com/fluentassertions/fluentassertions) from 6.7.0 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@6.7.0...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]>

src/Camelotia.Tests/Camelotia.Tests.csproj

@@ -8,7 +8,7 @@
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers</IncludeAssets>
     </PackageReference>
-    <PackageReference Include="FluentAssertions" Version="6.7.0" />
+    <PackageReference Include="FluentAssertions" Version="6.12.0" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.3.1" />
     <PackageReference Include="NSubstitute" Version="4.4.0" />
     <PackageReference Include="xunit" Version="2.4.2" />