Add autoroller task account into bot whitelist for author check

This will prevent failures like this one:
https://ci.chromium.org/p/v8/builds/b8945509831610302560

R=machenbach@chromium.org

No-Try: true
Bug: chromium:831171
Change-Id: I3f5c5ce6ea2148c22e4ef0b18495e10e37fd3fed
Reviewed-on: https://chromium-review.googlesource.com/1074367Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Sergiy Byelozyorov <sergiyb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53558}

PRESUBMIT.py

@@ -96,7 +96,9 @@ def _V8PresubmitChecks(input_api, output_api):
       input_api.AffectedFiles(include_deletes=True)):
     results.append(output_api.PresubmitError("Status file check failed"))
   results.extend(input_api.canned_checks.CheckAuthorizedAuthor(
-      input_api, output_api))
+      input_api, output_api, bot_whitelist=[
+        'v8-ci-autoroll-builder@chops-service-accounts.iam.gserviceaccount.com'
+      ]))
   return results