[Autoroll] Add liyuqian@ as sheriff back for engine->flutter roller

Bug: skia:8882
Change-Id: I81619dcfb8b128d3b334bf1181826b580f3e664a
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/201885
Reviewed-by: Eric Boren <borenet@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
diff --git a/autoroll/config/flutter-engine-flutter.json b/autoroll/config/flutter-engine-flutter.json
index 49610b7..91f6642 100644
--- a/autoroll/config/flutter-engine-flutter.json
+++ b/autoroll/config/flutter-engine-flutter.json
@@ -12,6 +12,9 @@
   "sheriff": [
     "https://rota-ng.appspot.com/legacy/sheriff_flutter_engine.json"
   ],
+  "sheriffBackup": [
+    "liyuqian@google.com"
+  ],
   "github": {
     "repoOwner": "flutter",
     "repoName": "flutter",