VOL-5137 - Create beta-release branch for voltha-system-tests

VERSION
-------
  o Post release bump major version string to avoid conflicts.

.gitreview
----------
  o Assign defaultbranch=master so branch problems are easier to detect.

Change-Id: I41e1a3fc11c5d7192e094668c7632736bf57eb74
diff --git a/VERSION b/VERSION
index 1717218..f92b44a 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.12.9-dev
+2.13.0-dev