update OTA script in tm-mainline-prod to the latest version.

The last change in tm-mainline-prod was last year (aosp/2040556), did a copy of current version in udc-dev.

Test: local ota
Bug: 279622634
Change-Id: I6563122f21d7213bfa7200e28cdfa69bd95aa3e2
Merged-In: Iaa317a3a4b8addbca8ea987aee9953c78fa1a679
diff --git a/scripts/update_payload/common.py b/scripts/update_payload/common.py
index 7c6ec8f..7139f6f 100644
--- a/scripts/update_payload/common.py
+++ b/scripts/update_payload/common.py
@@ -21,7 +21,7 @@
 
 import base64
 
-from update_payload import update_metadata_pb2
+import update_metadata_pb2
 from update_payload.error import PayloadError