The Boston City Council unanimously passed an ordinance Wednesday that would prevent the use of facial-recognition technology by the city government. The measure, proposed in May, does not change an existing practice, as the city does not use facial-recognition tools, according to the office of Mayor Martin J. Walsh. However, Councilor Ricardo Arroyo said that an update of the city’s surveillance technology had been set to potentially include facial-recognition elements. Arroyo and fellow city Councilor Michelle Wu argued that the danger of using the technology is the potential for false matches, especially among people of color. “It furthers racial inequity,” Arroyo said. Boston joins several other Massachusetts cities, including Springfield, to enact such a measure.