build(deps): Update FluentAssertions requirement from 6.11.* to 6.12.*

Updates the requirements on [FluentAssertions](https://github.com/fluentassertions/fluentassertions) to permit the latest version.
- [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
...

Signed-off-by: dependabot[bot] <[email protected]>

Packages.props

@@ -157,7 +157,7 @@
     <!-- Test time only -->
     <PackageReference Update="AutoFixture.AutoMoq" Version="4.18.*" />
     <PackageReference Update="coverlet.collector" Version="6.0.0" PrivateAssets="all" IncludeAssets="runtime; build; native; contentfiles; analyzers" />
-    <PackageReference Update="FluentAssertions" Version="6.11.*" />
+    <PackageReference Update="FluentAssertions" Version="6.12.*" />
     <PackageReference Update="ILogger.Moq" Version="1.1.*" />
     <PackageReference Update="Microsoft.AspNetCore.Mvc.Testing" Version="$(AspNetCoreMvcTestingVersion)" />
     <PackageReference Update="Microsoft.NET.Test.Sdk" Version="17.7.1" />