.mailmap: Add Hadriel Kaplan

Change-Id: Iddab5a98e47d90fe4a7e6fbf6b55bbb16e528415
Reviewed-on: https://code.wireshark.org/review/6136
Reviewed-by: Hadriel Kaplan <hadrielk@yahoo.com>
Tested-by: Hadriel Kaplan <hadrielk@yahoo.com>