Bump FSharp.Core in /RayTracerChallenge/XUnitTests

Bumps [FSharp.Core](https://github.com/dotnet/fsharp) from 7.0.300 to 7.0.400.
- [Release notes](https://github.com/dotnet/fsharp/releases)
- [Changelog](https://github.com/dotnet/fsharp/blob/main/release-notes.md)
- [Commits](https://github.com/dotnet/fsharp/commits)

---
updated-dependencies:
- dependency-name: FSharp.Core
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

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

RayTracerChallenge/RayTracerChallenge/RayTracer.fsproj

@@ -35,7 +35,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Update="FSharp.Core" Version="7.0.300" />
+    <PackageReference Update="FSharp.Core" Version="7.0.400" />
   </ItemGroup>
 
 </Project>

RayTracerChallenge/XUnitTests/XUnitTests.fsproj

@@ -41,7 +41,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Update="FSharp.Core" Version="7.0.300" />
+    <PackageReference Update="FSharp.Core" Version="7.0.400" />
   </ItemGroup>
 
 </Project>