Automatic: lumpy-factory - Updating to a new version number from 2305.20.0

Change-Id: I06beaf86e83a180386720e0dfcebc8449832c84a
diff --git a/chromeos/config/chromeos_version.sh b/chromeos/config/chromeos_version.sh
index e2b6f99..5e6490f 100755
--- a/chromeos/config/chromeos_version.sh
+++ b/chromeos/config/chromeos_version.sh
@@ -19,7 +19,7 @@
 # Release Branch number.
 # Increment by 1 for every release build on a branch.
 # Reset to 0 when increasing release build number.
-export CHROMEOS_BRANCH=20
+export CHROMEOS_BRANCH=21
 
 # Patch number.
 # Increment by 1 in case a non-scheduled branch release build is necessary.