By Alasdair Pal and Uditha Jayasinghe COLOMBO (Reuters) -Sri Lanka’s new prime minister said on Monday the crisis-hit nation was down to its last day of petrol, as the country’s power minister told citizens not to join the lengthy fuel queues that have galvanised weeks of anti-government protests. Ranil Wickremesinghe, appointed prime minister on Thursday, said in an address to the nation the country urgently needed $75 million in foreign exchange to pay for essential imports. “At the moment, we only have petrol stocks for a single day. The next couple of months will be the most difficult ones…