Incrementing VERSION to 84.0.4143.6

TBR=benmason@chromium.org

Change-Id: I3562e545572a20c2da1d1b1beb8fdd6fda68aba7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2194919
Reviewed-by: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/4143@{#8}
Cr-Branched-From: c49ce46-refs/heads/master@{#767161}

chrome/VERSION

@@ -1,4 +1,4 @@
 MAJOR=84
 MINOR=0
 BUILD=4143
-PATCH=5
+PATCH=6