Merge "Increment platform-tools version to 31.0.0." am: cfacb78776 am: 58c5cdc32a

Original change: https://android-review.googlesource.com/c/platform/development/+/1564416

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: If013d7774d63b9a5f24cb214943e2b7933830ad7