VOL-4028: Support fetching Onu PON Optical Information via SingleGetValueReq/Resp

Change-Id: I395aef64ee54ff75f172ac418ba73fcccd800f4f
diff --git a/go.mod b/go.mod
index 16d5b3a..1071030 100644
--- a/go.mod
+++ b/go.mod
@@ -10,7 +10,7 @@
 	github.com/jessevdk/go-flags v1.4.0
 	github.com/jhump/protoreflect v1.5.0
 	github.com/opencord/voltha-lib-go/v4 v4.3.0
-	github.com/opencord/voltha-protos/v4 v4.1.1
+	github.com/opencord/voltha-protos/v4 v4.1.4
 	github.com/stretchr/testify v1.4.0
 	go.etcd.io/etcd v0.0.0-20190930204107-236ac2a90522
 	golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45 // indirect