A 19-year-old who had pledged allegiance to the Islamic State militant group has confessed to plotting an attack on the Vienna leg of Taylor Swift’s Eras tour, a top Austrian security official said on Thursday. He had wanted to use homemade bombs and knives to kill people during Swift’s performance, said Omar Haijawi-Pirchner, director of state security and intelligence in the Austrian Interior Ministry. The 19-year-old did not have a concert ticket, but wanted to strike in the vicinity of the Ernst Happel Stadium. He was part of an Islamist network and already on the police’s radar, the offic…