NEW YORK — A Manhattan judge found New York City’s COVID-19 vaccine mandate can’t justify firing or putting on leave members of the city’s biggest police union. The city vowed an immediate appeal the ruling issued Friday by Supreme Court Judge Lyle E. Frank. In his ruling, Frank wrote that the city’s vaccine mandate is “invalid to the extent it has been used to impose a new condition of employment to current PBA members.” Frank ordered the reinstatement to the NYPD of any member of the Police Benevolent Association who was “wrongfully terminated” or put on unpaid leave for refusing to get vacc…