Hungary’s parliament approved a constitutional amendment on Monday that allows prime ministers to serve for a maximum of eight years, effectively barring former premier Viktor Orban from holding the role again.Prime Minister Peter Magyar ousted Orban in an election in April after 16 years, gaining a two-thirds majority in parliament that allows his party to roll back or change legislation passed by Orban’s Fidesz, including the constitution.The amendment was a key campaign promise of...