Incrementing VERSION to 91.0.4469.4

Change-Id: I89db438a56f05273a91e95aa03b7953c1d797f08
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2812240
Bot-Commit: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/4469@{#9}
Cr-Branched-From: 8563c4c-refs/heads/master@{#869727}

chrome/VERSION

@@ -1,4 +1,4 @@
 MAJOR=91
 MINOR=0
 BUILD=4469
-PATCH=3
+PATCH=4