README.md: update leaderboard

commit generated automatically from
https://github.com/fxnn/adventofcode2024/actions/runs/12455704019

Author: fxnn

README.md

@@ -5,7 +5,7 @@ See https://adventofcode.com/2024
 
 [//]: # (LEADERBOARD_BEGIN)
 
-> ![17 stars](https://img.shields.io/badge/17-%E2%AD%90_stars-gold) <br /> user **fxnn** (last one at 2024-12-20T22:07:11Z)
+> ![18 stars](https://img.shields.io/badge/18-%E2%AD%90_stars-gold) <br /> user **fxnn** (last one at 2024-12-22T16:00:26Z)
 
 [//]: # (LEADERBOARD_END)