contrib/gitdm: add Tsukasa as an individual contributor

I wasn't sure if you want to be added as an individual contributor or
an academic so please confirm.

Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Acked-by: Tsukasa OI <research_trasio@irq.a4lg.com>
Message-Id: <20221219121914.851488-7-alex.bennee@linaro.org>

contrib/gitdm/group-map-individuals

@@ -37,3 +37,4 @@ akihiko.odaki@gmail.com
 paul@nowt.org
 git@xen0n.name
 simon@simonsafar.com
+research_trasio@irq.a4lg.com