VOL-3978 - update to go 1.16.3

Change-Id: I3bc24ba662517badac4ddb238930550624c408a6
diff --git a/Makefile b/Makefile
index a213c83..2597c38 100644
--- a/Makefile
+++ b/Makefile
@@ -55,7 +55,7 @@
 	--build-arg LOCAL_PROTOS=${LOCAL_PROTOS}
 
 # tool containers
-VOLTHA_TOOLS_VERSION ?= 2.3.1
+VOLTHA_TOOLS_VERSION ?= 2.4.0
 
 GO                = docker run --rm --user $$(id -u):$$(id -g) -v ${CURDIR}:/app $(shell test -t 0 && echo "-it") -v gocache:/.cache -v gocache-${VOLTHA_TOOLS_VERSION}:/go/pkg voltha/voltha-ci-tools:${VOLTHA_TOOLS_VERSION}-golang go
 GO_JUNIT_REPORT   = docker run --rm --user $$(id -u):$$(id -g) -v ${CURDIR}:/app -i voltha/voltha-ci-tools:${VOLTHA_TOOLS_VERSION}-go-junit-report go-junit-report