PRAGUE—Czech President Milos Zeman appointed the leader of an opposition alliance Petr Fiala as prime minister on Sunday in a ceremony he performed from a plexiglass cubicle after testing positive for COVID-19. Fiala leads a bloc of five opposition parties that won an election in October, ousting the incumbent premier Andrej Babis and his allies. The new government will have to tackle a new wave of coronavirus infections and an energy crisis, after the collapse of a large electricity provider. The coalition has also said it plans to rework the 2022 state budget to reduce a large deficit. “The new government has a very complicated time ahead and many challenges… I want it to be a government of change for the future,” Fiala said at a news conference. He expected his cabinet to be appointed in mid-December. The new prime minister also called on people to get vaccinated against COVID-19 …