add Tshepang Mbambo to .mailmap

Author: tshepang

.mailmap

@@ -530,6 +530,7 @@ Tomas Koutsky <tomas@stepnivlk.net>
 Torsten Weber <TorstenWeber12@gmail.com>
 Torsten Weber <TorstenWeber12@gmail.com> <torstenweber12@gmail.com>
 Trevor Spiteri <tspiteri@ieee.org> <trevor.spiteri@um.edu.mt>
+Tshepang Mbambo <tshepang@gmail.com>
 Ty Overby <ty@pre-alpha.com>
 Tyler Mandry <tmandry@gmail.com> <tmandry@google.com>
 Tyler Ruckinger <t.ruckinger@gmail.com>