Update install workflow to support Go v1.18 (#134)

Command 'go get' can no longer be used to build packages starting Go v1.18 (https://go.dev/doc/go-get-install-deprecation). Kustomize version also needs to be updated to v4.5 since go install doesn't support exclude directives (kubernetes-sigs/kustomize#3618). The change has been tested on both Go v1.17 and Go v1.18 to ensure the Makefile works properly.

Makefile

@@ -138,7 +138,7 @@ kubetest2: ## Download kubetest2 locally if necessary.
 
 KUSTOMIZE = $(shell pwd)/bin/kustomize
 kustomize: ## Download kustomize locally if necessary.
-	$(call go-get-tool,$(KUSTOMIZE),sigs.k8s.io/kustomize/kustomize/v3@v3.8.7)
+	$(call go-get-tool,$(KUSTOMIZE),sigs.k8s.io/kustomize/kustomize/v4@v4.5.2)
 
 MOCKGEN = $(shell pwd)/bin/mockgen
 mockgen: ## Download mockgen locally if necessary.
@@ -153,7 +153,7 @@ TMP_DIR=$$(mktemp -d) ;\
 cd $$TMP_DIR ;\
 $(GO) mod init tmp ;\
 echo "Downloading $(2)" ;\
-GOBIN=$(PROJECT_DIR)/bin $(GO) get $(2) ;\
+GOBIN=$(PROJECT_DIR)/bin $(GO) install $(2) ;\
 rm -rf $$TMP_DIR ;\
 }
 endef