Prohibition against execution of an agreement with union or employee organization that includes maintenance of membership clause

It is unlawful for any person, firm, corporation or association of any kind operating in this state to execute an agreement with a union or employee organization of any kind that includes a maintenance of membership clause prohibiting employees from withdrawing from a union or employee organization prior to the agreement's expiration. This section shall not apply to a city, town, municipality or county, including a county having a metropolitan form of government.