set GOTOOLCHAIN min version when init go.work

When the golang version does not match the version used inside
the build container, dowloading the modules can fail with:

~~~
go: go.work requires go >= 1.21.13 (running go 1.21.11; GOTOOLCHAIN=local)
~~~

This PR makes set the GOTOOLCHAIN to set 1.21.0 as the min required
version and sets it in go.work file.

Signed-off-by: Martin Schuppert <mschuppert@redhat.com>

Makefile

@@ -164,7 +164,7 @@ test: manifests generate fmt vet envtest ginkgo ## Run tests.
 .PHONY: gowork
 gowork: export GOWORK=
 gowork: ## Generate go.work file to support our multi module repository
-	test -f go.work || go work init
+	test -f go.work || GOTOOLCHAIN=$(GOTOOLCHAIN_VERSION) go work init
 	go work use .
 	go work use ./api
 	go work sync
@@ -249,6 +249,7 @@ ENVTEST ?= $(LOCALBIN)/setup-envtest
 ## Tool Versions
 KUSTOMIZE_VERSION ?= v3.8.7
 CONTROLLER_TOOLS_VERSION ?= v0.11.1
+GOTOOLCHAIN_VERSION ?= go1.21.0
 
 KUSTOMIZE_INSTALL_SCRIPT ?= "https://github.com/raw/kubernetes-sigs/kustomize/master/hack/install_kustomize.sh"
 .PHONY: kustomize $(KUSTOMIZE)