MILAN — The international jury of the Venice Biennale resigned Thursday, just nine days before the world’s oldest and most important contemporary art fair opens, amid tensions over Russia’s participation and the panel’s decision to bar prizes for countries accused of crimes against humanity. The Biennale said in a statement that the jury, made up of the president, Solange Farkas, and Zoe Butt, Elvira Dyangani Ose, Marta Kuzma and Giovanna Zapperi, had resigned. The brief statement didn’t provide an explanation for the highly unusual move.It came just days after the jury had announced it would not award prizes to countries...