LOS ANGELES (Reuters) – Soul music superstar Aretha Franklin on Friday canceled an upcoming concert in Michigan, citing recovery from health issues that forced her to postpone concerts earlier this year. Franklin, 71, said in an open letter to her fans that she was canceling her July 27 show at the DTE Energy Pine Knob Theater in Clarkston, Michigan, due to "miscalculation" of the end of her treatment. "It would be totally disruptive to stop them now and go into concert with total success right at the door," Franklin said. …