Bump FluentValidation from 10.3.6 to 10.4.0 in /src (#437)

Bumps [FluentValidation](https://github.com/JeremySkinner/fluentvalidation) from 10.3.6 to 10.4.0.
- [Release notes](https://github.com/JeremySkinner/fluentvalidation/releases)
- [Changelog](https://github.com/FluentValidation/FluentValidation/blob/main/Changelog.txt)
- [Commits](FluentValidation/FluentValidation@10.3.6...10.4.0)

---
updated-dependencies:
- dependency-name: FluentValidation
  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>

src/AzureIoTHub.Portal/Client/AzureIoTHub.Portal.Client.csproj

@@ -7,7 +7,7 @@
 
   <ItemGroup>
     <PackageReference Include="Blazored.Modal" Version="6.0.1" />
-    <PackageReference Include="FluentValidation" Version="10.3.6" />
+    <PackageReference Include="FluentValidation" Version="10.4.0" />
     <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly" Version="6.0.3" />
     <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.Authentication" Version="6.0.3" />
     <PackageReference Include="Microsoft.AspNetCore.Components.WebAssembly.DevServer" Version="6.0.3" PrivateAssets="all" />