Verdi’s “La Traviata,” the next offering from The Met: Live in HD, will be shown at Guild Hall on Saturday at 1 p.m. Sonya Yoncheva will sing the role of Violetta, the tragic courtesan, opposite Michael Fabiano as her lover, Alfredo, and Thomas Hampton as his father, Germont. Tickets are $22, $20 for members, and $15 for students.