Add roller SA and myself to OWNERS

Change-Id: If62edd6ee1b880f6179581345807f8ad867e5b3c
Reviewed-on: https://pigweed-review.googlesource.com/c/open-dice/+/151490
Pigweed-Auto-Submit: Rob Mohr <mohrr@google.com>
Reviewed-by: Darren Krahn <dkrahn@google.com>
Commit-Queue: Auto-Submit <auto-submit@pigweed.google.com.iam.gserviceaccount.com>
Reviewed-by: Andrew Scull <ascull@google.com>
diff --git a/OWNERS b/OWNERS
index db8d2a7..58d8a6a 100644
--- a/OWNERS
+++ b/OWNERS
@@ -1,2 +1,4 @@
 ascull@google.com
 dkrahn@google.com
+mohrr@google.com
+pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com