use the module proxy and force module mode

Makefile

@@ -20,6 +20,8 @@ REPO_ROOT=$(PWD)
 # autodetect host GOOS and GOARCH by default, even if go is not installed
 GOOS=$(shell hack/goos.sh)
 GOARCH=$(shell hack/goarch.sh)
+# use the official module proxy by default
+GOPROXY=https://proxy.golang.org
 # default build image
 GO_VERSION=1.12.5
 GO_IMAGE=golang:$(GO_VERSION)
@@ -49,6 +51,8 @@ kind: make-cache
 		-e GOCACHE=/go/cache \
 		-v $(REPO_ROOT):$(CONTAINER_REPO_DIR) \
 		-w $(CONTAINER_REPO_DIR) \
+		-e GO111MODULE=on \
+		-e GOPROXY=$(GOPROXY) \
 		-e CGO_ENABLED=0 \
 		-e GOOS=$(GOOS) \
 		-e GOARCH=$(GOARCH) \