CEO & CTORaces in iGP Manager are all in the GMT / UTC timezone. They do not change with the local clocks of any particular country/region. It is up to league hosts if they wish to change the race time after a local clock change.
Why doesn't iGP change it automatically? Because we have an international audience. For example, if we moved every race when the clocks in America changed, it would throw off everyone else in the world who isn't in America, and vice versa.
...why doesn't iGP change it automatically? Since people generally continue to ask why we can't do this even after being offered the explanation above, here is a more detailed answer: Within leagues there are people from different timezones and regions. Some leagues even have people from different continents racing together, e.g. American, British, Australian etc. If the clocks moved for any one of these regions it would throw off everyone else in the league, whose clocks didn't move at the same time. Therefore, by keeping the races in GMT/UTC it is fair for everyone, and the race times will only change when your clocks change locally, which is something you can act to anticipate, as you'll be getting reminders all day long that the clocks are changing. This is not the case when clocks change in other parts of the world. You wouldn't get any reminders for the clocks changing on another continent and would be completely surprised if your race times changed because of it.