Adds JetBrains.Annotations to reduce amount of false positives by static code analysis

src/Web/Infrastructure/CustomExceptionHandler.cs

@@ -1,6 +1,8 @@
 using Hutopy.Application.Common.Exceptions;
 using Microsoft.AspNetCore.Diagnostics;
 using Microsoft.AspNetCore.Mvc;
+using ProblemDetails = Microsoft.AspNetCore.Mvc.ProblemDetails;
+using ValidationException = Hutopy.Application.Common.Exceptions.ValidationException;
 
 namespace Hutopy.Web.Infrastructure;