VOL-1643 Update voltha-lib-go to use voltha-protos v3.0.0

and bump up the version to 3.0.0. voltha-protos is modified to be
compatible with the java language proto compilation. It's a major
change and a major version change has been made.

Change-Id: Ifb93430567ddf96aaa0fbf6e5853aad9e1070f6f
diff --git a/pkg/mocks/etcd_server_test.go b/pkg/mocks/etcd_server_test.go
index 90a3654..c2efd58 100644
--- a/pkg/mocks/etcd_server_test.go
+++ b/pkg/mocks/etcd_server_test.go
@@ -18,7 +18,7 @@
 
 import (
 	"fmt"
-	"github.com/opencord/voltha-lib-go/v2/pkg/db/kvstore"
+	"github.com/opencord/voltha-lib-go/v3/pkg/db/kvstore"
 	"github.com/phayes/freeport"
 	"github.com/stretchr/testify/assert"
 	"os"