VOL-3978 - update to go 1.16.3

Change-Id: I4a1c78722b3e4019dfd288fa9c89b7d90924050a
diff --git a/Makefile b/Makefile
index 0be6996..210fd0e 100644
--- a/Makefile
+++ b/Makefile
@@ -51,7 +51,7 @@
 	--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