Updating trunk VERSION from 3970.0 to 3971.0

# This is an automated release commit.
# Do not revert without consulting chrome-pmo@google.com.
NOAUTOREVERT=true
TBR=govind@chromium.org

Change-Id: Ib11628ca0700e5f469d1a575a7bce6c57474d2a2
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1921451Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#716065}

chrome/VERSION

 MAJOR=80
 MINOR=0
-BUILD=3970
+BUILD=3971
 PATCH=0