Updating trunk VERSION from 4317.0 to 4318.0

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

Change-Id: I36a387916e62a13bda59b227b0a84a2690c23668
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2522891Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/heads/master@{#824712}

chrome/VERSION

 MAJOR=88
 MINOR=0
-BUILD=4317
+BUILD=4318
 PATCH=0