set GOTOOLCHAIN to GO_VERSION in Makefile

Author: prezha

Makefile

@@ -38,7 +38,7 @@ RPM_REVISION ?= 0
 GO_VERSION ?= 1.23.4
 # set GOTOOLCHAIN to GO_VERSION to override any toolchain version specified in
 # go.mod (ref: https://go.dev/doc/toolchain#GOTOOLCHAIN)
-export GOTOOLCHAIN := $(GO_VERSION)
+export GOTOOLCHAIN := go$(GO_VERSION)
 # update this only by running `make update-golang-version`
 GO_K8S_VERSION_PREFIX ?= v1.33.0