fix aoc end date

plugins/aoc.lisp

@@ -5,7 +5,7 @@
 
 (defparameter +api-uri+ "https://adventofcode.com/2020/leaderboard/private/view/24158.json")
 (defparameter +leader-board-link+ "https://adventofcode.com/2020/leaderboard/private/view/24158")
-(defparameter +advent-time+ (encode-universal-time 0 0 8 25 12 2020 3))
+(defparameter +advent-time+ (encode-universal-time 0 0 8 25 12 2020 -3))
 
 (defmethod poller-request ((module (eql :aoc)) method &rest params)
   (declare (ignorable params))