Incrementing VERSION to 78.0.3904.18

TBR=kariah@chromium.org

Change-Id: I04dfc840be173a08b0a1a8da42e14809c4f146e0
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1808461
Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/3904@{#261}
Cr-Branched-From: 675968a8c657a3bd9c1c2c20c5d2935577bbc5e6-refs/heads/master@{#693954}
1 file changed