Update mailmap for estebank

.mailmap

@@ -78,6 +78,7 @@ Eric Holk <eric.holk@gmail.com> <eholk@mozilla.com>
 Eric Holmes <eric@ejholmes.net>
 Eric Reed <ecreed@cs.washington.edu> <ereed@mozilla.com>
 Erick Tryzelaar <erick.tryzelaar@gmail.com> <etryzelaar@iqt.org>
+Esteban Küber <esteban@kuber.com.ar> <estebank@users.noreply.github.com> <esteban@commure.com> <github@kuber.com.ar>
 Evgeny Sologubov
 Falco Hirschenberger <falco.hirschenberger@gmail.com> <hirschen@itwm.fhg.de>
 Felix S. Klock II <pnkfelix@pnkfx.org> Felix S Klock II <pnkfelix@pnkfx.org>