VOL-5142 - Create beta-release branch for ofagent-go

VERSION
-------
  o Bump version string for beta release.

.gitreview
----------
  o Assign defaultbranch=voltha-2.12 for release branch checkins.

Change-Id: I663fa0ca2bded04e3d34c5093310c69cc7c438a1
diff --git a/.gitreview b/.gitreview
index c04b89f..77db3c4 100644
--- a/.gitreview
+++ b/.gitreview
@@ -3,3 +3,4 @@
 port=29418
 project=ofagent-go.git
 defaultremote=origin
+defaultbranch=voltha-2.12
\ No newline at end of file