By Daniel Wiessner (Reuters) -Alphabet Inc’s Google violated U.S. labor law by refusing to bargain with a union representing contract workers for YouTube Music, a federal agency has ruled. The National Labor Relations Board (NLRB) in a decision on Wednesday rejected claims by Google, which owns YouTube, that it should not be considered the employer of workers provided by staffing firm Cognizant Technology Solutions. The group of YouTube Music content operation workers voted 41-0 last April to join the Alphabet Workers Union, which was formed three years ago to organize the company’s employees….