Incrementing VERSION to 120.0.6099.56

Change-Id: I16208e70db40d4a26d6ea56946591f3a97918c7d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5069314
Bot-Commit: Chrome Release Bot (LUCI) <chrome-official-brancher@chops-service-accounts.iam.gserviceaccount.com>
Cr-Commit-Position: refs/branch-heads/6099@{#1192}
Cr-Branched-From: e6ee450-refs/heads/main@{#1217362}

chrome/VERSION

@@ -1,4 +1,4 @@
 MAJOR=120
 MINOR=0
 BUILD=6099
-PATCH=55
+PATCH=56