Add sdefresne as an EMEA based OWNERS

Bug: none
Change-Id: I41e81af7dc24df350f718226f2b4b90b7d6b2fa8
Reviewed-on: https://gn-review.googlesource.com/c/gn/+/13160
Reviewed-by: David Turner <digit@google.com>
Reviewed-by: Brett Wilson <brettw@chromium.org>

OWNERS

diff --git a/OWNERS b/OWNERS
index d78697c..0571570 100644
--- a/OWNERS
+++ b/OWNERS
@@ -1,3 +1,4 @@
 brettw@chromium.org
 phosek@chromium.org
 scottmg@chromium.org
+sdefresne@chromium.org