NorthwindSlimContextFactory.cs

public class NorthwindSlimContextFactory : IDesignTimeDbContextFactory<NorthwindSlimContext>
{
    public NorthwindSlimContext CreateDbContext(string[] args)
    {
        var optionsBuilder = new DbContextOptionsBuilder<NorthwindSlimContext>();
        optionsBuilder.UseSqlite("Data Source=northwindslim.db");
        return new NorthwindSlimContext(optionsBuilder.Options);
    }
}