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 <[email protected]>

Author: stuggi

Makefile

@@ -269,6 +269,7 @@ KUSTOMIZE_VERSION ?= v3.8.7
 CONTROLLER_TOOLS_VERSION ?= v0.11.1
 CRD_MARKDOWN_VERSION ?= v0.0.3
 KUTTL_VERSION ?= 0.17.0
+GOTOOLCHAIN_VERSION ?= go1.21.0
 
 KUSTOMIZE_INSTALL_SCRIPT ?= "https://raw.githubusercontent.com/kubernetes-sigs/kustomize/master/hack/install_kustomize.sh"
 .PHONY: kustomize
@@ -437,7 +438,7 @@ golint: get-ci-tools
 
 .PHONY: 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 ./apis
 	go work sync