It shall be the duty and responsibility of the governing authority of each county of this state to keep the county courthouse and the county offices maintained therein open during normal working hours for the transaction of the public's business. As used in this Code section, "normal working hours" means a minimum of 40 working hours during each calendar week, except for those weeks during which public and legal holidays, which are recognized and designated as such by Georgia law or by the governing authority of the county, are observed.