[VOL-5429] - update voltha-lib-go version to 7.6.6

Change-Id: Icfb05034b265fb758603234764e624c95c5b2762
Signed-off-by: Sridhar Ravindra <sridhar.ravindra@radisys.com>
diff --git a/VERSION b/VERSION
index e9548af..7d08a22 100755
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.12.15
+2.12.16