Can't get Dependency Injection's Configure<> to work in .net core console application

Question

I'm trying to implement dependency injection in a .net core console application, but I can't manage to configure MySettings

public static class Program
{
    public static IConfigurationRoot Configuration { get; private set; }

    public static void Main(string[] args)
    {
        var builder = new ConfigurationBuilder()
           .AddJsonFile("appsettings.json", true, true)               
        Configuration = builder.Build();

        var serviceProvider = BuildDi(Configuration);

        serviceProvider.GetRequiredService<Bootstrapper>().DoThings();
    }

    private static IServiceProvider BuildDi(IConfigurationRoot configuration)
    {
        var services = new ServiceCollection();
        services.Configure<MySettings>(configuration.GetSection("MySettings"));
        services.AddSingleton<Bootstrapper>();

        return services.BuildServiceProvider();            
    }
}

MySettings class is as easy as

public class MySettings
{
    public string MyVariable { get; set; }        
}

while appsettings.json is

{
  "MySettings": {
    "MyVariable": "test"
  }
}

and Bootstrapper is

public class Bootstrapper
{
    private readonly MySettings _settings;

    public Bootstrapper(IOptions<MySettings> settings)
    {
        _settings = settings.Value;
    }

    public void DoThings()
    {
        Console.WriteLine(_settings.MyVariable);
    }
}

but, when i'm trying to access Mysettings.MyVariable, i get null.

I can't understand what am I missing, since I have no problem doing the same exact thing in a asp.net core type project.

(yes, it's kinda like Access configuration through dependency injection in .NET Core console application, but with some steps further)