added line to AUTHORS file

Author: Code-Hex

AUTHORS

@@ -55,6 +55,7 @@ Julien Schmidt <go-sql-driver at julienschmidt.com>
 Justin Li <jli at j-li.net>
 Justin Nuß <nuss.justin at gmail.com>
 Kamil Dziedzic <kamil at klecza.pl>
+Kei Kamikawa <x00.x7f.x86 at gmail.com>
 Kevin Malachowski <kevin at chowski.com>
 Kieron Woodhouse <kieron.woodhouse at infosum.com>
 Lennart Rudolph <lrudolph at hmc.edu>