Structure of 1,1,2,2,3,3‐hexacarbonyl‐1,2;2,3;3,1‐tris(μ‐diphenylphosphido)‐triangulo‐tricobalt(I)(3Co–Co) acetonitrile solvate, [Co3{P(C6H5)2}3(CO)6].C2H3N