“ToasT,” a new play by the acclaimed spoken-word artist and Tony Award-winning writer Lemon Andersen and directed by Elise Thoron, will be given a staged reading at Guild Hall tonight at 8. A Public Theater commission first presented at the Public’s Under the Radar festival, “ToasT” weaves characters from black oral narratives into a drama about a group of inmates at Attica during the 1971 riots at the prison.