Add my former address to .mailmap

Author: bash

.mailmap

@@ -543,6 +543,7 @@ Takashi Idobe <idobetakashi@gmail.com>
 Takayuki Maeda <takoyaki0316@gmail.com>
 Tamir Duberstein <tamird@gmail.com> Tamir Duberstein <tamird@squareup.com>
 Tatsuyuki Ishi <ishitatsuyuki@gmail.com>
+Tau Gärtli <git@tau.garden> <ruben.schmidmeister@icloud.com>
 Tero Hänninen <lgvz@users.noreply.github.com> Tero Hänninen <tejohann@kapsi.fi>
 The8472 <git@infinite-source.de>
 Theo Belaire <theo.belaire@gmail.com> Theo Belaire <tyr.god.of.war.42@gmail.com>