Bump FluentValidation from 11.11.0 to 12.0.0 in /src

Bumps [FluentValidation](https://github.com/JeremySkinner/fluentvalidation) from 11.11.0 to 12.0.0.
- [Release notes](https://github.com/JeremySkinner/fluentvalidation/releases)
- [Changelog](https://github.com/FluentValidation/FluentValidation/blob/main/Changelog.txt)
- [Commits](FluentValidation/FluentValidation@11.11.0...12.0.0)

---
updated-dependencies:
- dependency-name: FluentValidation
  dependency-version: 12.0.0
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

src/Directory.Packages.props

@@ -4,7 +4,7 @@
     <CentralPackageTransitivePinningEnabled>true</CentralPackageTransitivePinningEnabled>
   </PropertyGroup>
   <ItemGroup>
-    <PackageVersion Include="FluentValidation" Version="11.11.0" />
+    <PackageVersion Include="FluentValidation" Version="12.0.0" />
     <PackageVersion Include="FluentValidation.DependencyInjectionExtensions" Version="11.11.0" />
     <PackageVersion Include="GraphQL" Version="8.5.0" />
     <PackageVersion Include="GraphQL.MicrosoftDI" Version="8.5.0" />