Golshifteh Farahani is the protagonist of Anup Singh’s third feature, “The Song of Scorpions,” and the film, world premiering at Locarno 2017, is another stepping stone for an actress who keeps on challenging herself. In the film, Farahani’s character Nooran lives in India’s Rajasthan desert, training to heal scorpion bites with her songs, until tragedy envelops her.