MADRID (Reuters) – German automaker Mercedes-Benz plans to invest 1.2 billion euros in its Vitoria plant in northern Spain after workers backed a new labour agreement, unions UGT and CCOO said on Tuesday. About 57% of the plant’s nearly 5,000 workers voted in favour of a deal that defines working conditions and pay raises until 2026, allowing the automaker to invest in the production of new models and electric vehicles, the unions said in separate statements. Mercedes-Benz was not immediately available for comment. The company has said it expects to assemble 158,000 vehicles in Vitoria, its se…