CAPE TOWN—Caster Semenya, denied an opportunity to win a third successive Olympic 800 meters gold, will on Friday attempt to qualify for the Tokyo Games over 5,000 meters. Semenya will run in a meeting in Durban where she must dramatically improve her personal best over the distance to be able to go to the Olympics in two month’s time. The 30-year-old South African is banned from competing in any race from 400 meters to a mile after World Athletics ruled in 2018 that in order to ensure fair competition women with high natural testosterone levels must take drugs to reduce them to compete in middle-distance races. Semenya, who refuses to take medication to alter her testosterone levels, has challenged the ruling but seen several appeals dismissed. The 5,000 meters is therefore her best chance to go to the Tokyo Games. Semenya set a time of 15:52.28 in winning the South …