At the end of each fiscal year, the amount of each appropriation provided for in this part, except for the mandatory appropriations required by the Constitution of Georgia, remaining unexpended and not contractually obligated in writing shall lapse and cease to be available; and the state treasury shall not pay any unallotted appropriations and shall make the necessary adjustments in its appropriation accounts to charge off the amount of the lapsed appropriations. All appropriated funds, except for the mandatory appropriations required by the Constitution of Georgia, remaining unexpended and not contractually obligated at the expiration of the General Appropriations Act shall lapse.