.mailmap: add an alias for Julien Isorce

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/1999>
diff --git a/.mailmap b/.mailmap
index f77b8a3..7da6b9f 100644
--- a/.mailmap
+++ b/.mailmap
@@ -324,6 +324,7 @@
 Julien Cristau <jcristau@debian.org> <julien.cristau@logilab.fr>
 
 Julien Isorce <j.isorce@samsung.com> <julien.isorce@gmail.com>
+Julien Isorce <j.isorce@samsung.com> <jisorce@oblong.com>
 
 Kalyan Kondapally <kalyan.kondapally@intel.com> <kondapallykalyancontribute@gmail.com>