Mayor Bill de Blasio was excluded from participating in New York’s major Columbus Day event Monday, The Post has learned. The head of the Columbus Citizens Foundation confirmed that de Blasio was not invited to speak at this year’s alternative event to the Columbus Day parade that was canceled because of the coronavirus pandemic. The foundation’s virtual “2020 Columbus Citizens Foundation Italian Heritage & Achievement Special” event was televised on WABC-TV from 12:30 p.m. to 2 p.m.