Hereafter cities of the second class shall have power and authority to regulate, by ordinance, sales of merchandise at public auction, and to fix and enforce penalties for the violation of the provisions of such ordinances: Provided, however, That this authority shall not apply to judicial sales, sales by executors or administrators, or to sales by or in behalf of licensed pawnbrokers, or unredeemed pledges, in the manner provided by law.
53 P.S. § 23135