AUTHORS: update "as of" info
Forgot to update last time.
# Authors of mruby (mruby developers)
-## The List of Contributors sorted by number of commits (as of 2022-11-08 98cc660)
+## The List of Contributors sorted by number of commits (as of 2022-12-08 a7e304a)
8719 Yukihiro "Matz" Matsumoto (@matz)*
586 KOBAYASHI Shuji (@shuujii)
