The Pittsburgh Opera concludes its 2017-18 season with Donizetti’s “L’Elisir d’Amore.” Donizetti’s 36th opera, and one of his most popular, is set to star Russian soprano Ekaterina Siurina and American tenor Dimitri Pittas in the lead roles. Zachary Nelsons will sing Belcore while Paolo Pecchioli will portray Dulcamara. The new production by Daniel Slater, which was presented at the Houston Grand {…}