URUBICHÁ, Bolivia — Nestled in the Bolivian Amazon, the small, majority-Indigenous town of Urubicha has become an unexpected hub of violin makers, also known as luthiers.Out of a population of some 8,000 people, most of whom are native Guarayos, some 40-50 work directly in the trade, local resident Waldo Papu tells AFP.“I have not seen a place where so many violins are made,”