Updating trunk VERSION from 3975.0 to 3976.0

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

Change-Id: Ic7dee6be5e1ede4d6d979e8b926ab0fd81b7609c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1930410Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#718414}

chrome/VERSION

 MAJOR=80
 MINOR=0
-BUILD=3975
+BUILD=3976
 PATCH=0