[OWNERS] Add ewout@google.com

Change-Id: I2c53eb3d8c47ce84f210514c7833fdf2d71c3bcc
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/21341
Reviewed-by: Ewout van Bekkum <ewout@google.com>
Reviewed-by: Keir Mierle <keir@google.com>
Commit-Queue: Rob Mohr <mohrr@google.com>

OWNERS

diff --git a/OWNERS b/OWNERS
index 1502d13..f584bdc 100644
--- a/OWNERS
+++ b/OWNERS
@@ -1,5 +1,6 @@
 amontanez@google.com
 davidrogers@google.com
+ewout@google.com
 frolv@google.com
 hepler@google.com
 jethier@google.com