By Uditha Jayasinghe and Devjyot Ghoshal COLOMBO (Reuters) – Sri Lanka’s finance minister on Friday said that the crisis-hit country must urgently restructure its debt and seek external help, while the main opposition threatened a no-confidence motion and business leaders warned that exports could plummet. The heavily indebted country has little money left to pay for imports, leading to crippling shortages of fuel, power, food and, increasingly, medicine. Street protests have been held nearly non-stop for more than a month, despite a five-day state of emergency and a two-day curfew. “We cannot…