By Michael Holden and Andrew MacAskill LONDON (Reuters) – The Scottish government cannot hold a second referendum on independence without approval from the British parliament, the United Kingdom’s top court ruled on Wednesday, dealing a hammer blow to nationalists’ hopes of holding a vote next year. Scottish First Minister Nicola Sturgeon, leader of the pro-independence Scottish National Party (SNP), had announced earlier this year she intended to hold an advisory vote on secession next October, but that it had to be lawful and internationally recognised. After the UK Supreme Court ruled she c…