By Devjyot Ghoshal and Uditha Jayasinghe COLOMBO (Reuters) -Sri Lanka will need about $3 billion in external assistance over the next six months to help restore supplies of essential items including fuel and medicine, Finance Minister Ali Sabry told Reuters on Saturday. The island nation of 22 million people has been hit by power cuts and shortages which have drawn protesters out on to the streets and put President Gotabaya Rajapaksa under mounting pressure. “It’s a Herculean task,” said Sabry in his first interview since taking office this week, referring to finding $3 billion in bridge finan…