It took a while to find the relevant law because the Georgia website stinks without a table of contents and a search function that fails to find things. (
Georgia Code 21-2-501) If I remember correctly, Georgia used to have some complicated rules as to when a plurality could and whether it needed to be at least 40 or 45%, but it looks like they've simplified them. Municipalities with less than 100,000 people can have, if they so choose, election by plurality, with no lower limit as how big a plurality it must be. All other elections except for presidential electors must have a majority.