All governing authorities of the State of Nebraska, and governmental subdivisions thereof, and every person acting as purchasing agent for the State of Nebraska, or any governmental subdivision thereof, shall, in awarding contracts for public works, require all contractors bidding on public works to file with such authority a statement that he is complying with, and will continue to comply with, fair labor standards in the pursuit of his business and in the execution of the contract on which he is bidding. The governing authorities shall also require to be written into each and every contract for public works, in addition to such other provisions as are necessary and prescribed by law, a provision that in the execution of such contract fair labor standards shall be maintained; Provided, no agency or department of the State of Nebraska shall make any requirements, because of the provisions of sections 73-101 to 73-104, that will increase the cost to the state of merchandise, materials, supplies or services. This section shall not apply to such governing authorities that prescribe, in the terms of their contracts for public works, provisions governing the hours of labor, rates of pay, and conditions of employment.