use go install instead of go get in Makefile

Signed-off-by: Sanskar Jaiswal <sanskar.jaiswal@weave.works>

Makefile

@@ -105,7 +105,7 @@ docker-push:
 CONTROLLER_GEN = $(shell pwd)/bin/controller-gen
 .PHONY: controller-gen
 controller-gen: ## Download controller-gen locally if necessary.
-	$(call go-get-tool,$(CONTROLLER_GEN),sigs.k8s.io/controller-tools/cmd/controller-gen@v0.7.0)
+	$(call go-install-tool,$(CONTROLLER_GEN),sigs.k8s.io/controller-tools/cmd/controller-gen@v0.5.0)
 
 # Find or download gen-crd-api-reference-docs
 gen-crd-api-reference-docs:
@@ -132,18 +132,18 @@ install-envtest: setup-envtest
 ENVTEST = $(shell pwd)/bin/setup-envtest
 .PHONY: envtest
 setup-envtest: ## Download envtest-setup locally if necessary.
-	$(call go-get-tool,$(ENVTEST),sigs.k8s.io/controller-runtime/tools/setup-envtest@latest)
+	$(call go-install-tool,$(ENVTEST),sigs.k8s.io/controller-runtime/tools/setup-envtest@latest)
 
-# go-get-tool will 'go get' any package $2 and install it to $1.
+# go-install-tool will 'go install' any package $2 and install it to $1.
 PROJECT_DIR := $(shell dirname $(abspath $(lastword $(MAKEFILE_LIST))))
-define go-get-tool
+define go-install-tool
 @[ -f $(1) ] || { \
 set -e ;\
 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