The provisions of this article shall not be applicable to any contracts made by a municipality pursuant to the provisions of Act No. 4 adopted at the 1956 Second Special Session of the Legislature of Alabama, as amended, which relates to the promotion of trade by inducing commercial enterprises to locate in the state and which confers on municipalities having a population not exceeding 100,000 inhabitants, according to the last or any subsequent federal census, powers with respect to the acquisition, leasing and financing of projects suitable for use by certain commercial enterprises.