As they ^^^ said, because Georgia isn’t finished with this year’s election. They have two Senate seats open (most of the time it’s only one at a time), and the Senate is currently at 50 R – 48 D. If the Democrats pick up those two seats, it’ll be a 50–50 split, with the (incoming Democratic) VP the tie-vote breaker. So it’s a big, big deal.
It also happens to be the case that Georgia was one of the states in heavy contention for the presidential election and one of those that Trump has tried and is still trying to overturn. He held a “victory rally” there on Dec. 5th, nominally to support the two Republican candidates for the Senate but mostly (of course) to rant about himself.
Stacey Abrams, who was defeated for governor, was by all accounts a powerful influence in swinging Georgia for Biden. We’ll be hearing more of her.