just install the thing

Makefile

@@ -27,17 +27,4 @@ test:
 
 MOCKGEN := mockgen
 mockgen: ## Download conversion-gen locally if necessary.
-	$(call go-get-tool,$(MOCKGEN),github.com/golang/mock/mockgen)
-
-PROJECT_DIR := $(shell dirname $(abspath $(lastword $(MAKEFILE_LIST))))
-define go-get-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) ;\
-rm -rf $$TMP_DIR ;\
-}
-endef
+	go get github.com/golang/mock/mockgen; go install github.com/golang/mock/mockgen;