(Credit: Lars Borges) The Seattle Symphony Orchestra has announced its 2020-21 season. Here is a look at the vocal highlights of the season. The first major vocal highlight of the season will be Audra McDonald performing music from “Porgy and Bess,” “Carousel,” and other notable Broadway tuned alongside conductor Andy Einhorn. Performance Date: Oct. 20, 2020  Soprano  Nuria Rial will take {…}