[VOL-5129] - Create beta-release branch for voltha-protos

VERSION
-------
  o Bump string post release to next major *-dev version.

.gitreview
----------
  o Assign defaultbranch=master to make release branch conflicts easier to notice.

Change-Id: I0c850af4bfc5718945e59629ef4fa336cd105de0
diff --git a/VERSION b/VERSION
index 2e43841..a49cad2 100755
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-5.4.11-dev
+5.5.0-dev