Use voltha-protos version 4.0.2
Bump major version of voltha-lib-go to 4.0.0 as this change results
in incompatible API version compared to previous version

Change-Id: I1def58361fb1d85f07d6948ebf1ffb7a92eb0d4c
diff --git a/pkg/probe/probe.go b/pkg/probe/probe.go
index 732d6df..f13f257 100644
--- a/pkg/probe/probe.go
+++ b/pkg/probe/probe.go
@@ -18,7 +18,7 @@
 import (
 	"context"
 	"fmt"
-	"github.com/opencord/voltha-lib-go/v3/pkg/log"
+	"github.com/opencord/voltha-lib-go/v4/pkg/log"
 	"net/http"
 	"sync"
 )