CHROMIUM: Add asemjonovs to OWNERS file

asemjonovs joining downstreamers list

BUG=none
TEST=none

Change-Id: I9e12e57db4504790e2f133e0c83eff01a285075b
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/zephyr/+/5901918
Tested-by: Al Semjonovs <asemjonovs@google.com>
Auto-Submit: Al Semjonovs <asemjonovs@google.com>
Commit-Queue: ChromeOS Auto Runner <chromeos-auto-runner@chromeos-bot.iam.gserviceaccount.com>
Reviewed-by: Jeremy Bettis <jbettis@chromium.org>
Commit-Queue: Jeremy Bettis <jbettis@chromium.org>

OWNERS

@@ -1,6 +1,7 @@
 # This list should be kept in sync with the downstreaming rotation:
 # https://rotations.corp.google.com/rotation/4735002850885632
 
+asemjonovs@google.com
 dawidn@google.com
 fabiobaltieri@google.com
 honscheid@google.com