[infra] Fix asset_utils import

Change-Id: Ibb1c563fccae980ad23fac7c41bc5dc91a9925c0
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/404876
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
diff --git a/infra/bots/assets/assets.py b/infra/bots/assets/assets.py
index a5284dd..2a1f1ac 100755
--- a/infra/bots/assets/assets.py
+++ b/infra/bots/assets/assets.py
@@ -10,7 +10,7 @@
 
 
 import argparse
-import asset_utils
+from . import asset_utils
 import os
 import shutil
 import subprocess