AUTHORS: update "as of" info for `year`
The AUTHORS file was last published on January 8th 2023
# Authors of mruby (mruby developers)
-## The List of Contributors sorted by number of commits (as of 2022-01-08 4462e3d)
+## The List of Contributors sorted by number of commits (as of 2023-01-08 4462e3d)
8860 Yukihiro "Matz" Matsumoto (@matz)*
586 KOBAYASHI Shuji (@shuujii)
