Retired employees of a public agency, other than a school district, or eligible surviving spouses of such retired employees, on approval of the governing body of such public agency, in addition to any other purposes authorized in this article, may authorize deductions to be made from their retirement or survivors’ allowances for the payment of dues in any bona fide association whose membership is comprised in whole or in part of retired employees of such public agency in accordance with provisions made by the governing body of the public agency.