Fix Helm @ 2.16.0 download is Error 403

Helm v2 is EOL, the latest release is v2.17.0. (Upgrade to that version)

Use new Helm download links from get.helm.sh, as Google Cloud storage
bucket for Helm downloads has apparently been un-published.

Signed-off-by: Kingdon Barrett <kingdon@weave.works>

Makefile

@@ -8,7 +8,7 @@ TEST_FLAGS?=
 BATS_COMMIT := 3a1c2f28be260f8687ff83183cef4963faabedd6
 SHELLCHECK_VERSION := 0.7.0
 SHFMT_VERSION := 2.6.4
-HELM_VERSION := 2.16.0
+HELM_VERSION := 2.17.0
 
 include docker/kubectl.version
 include docker/kustomize.version
@@ -129,7 +129,7 @@ cache/%/kustomize-$(KUSTOMIZE_VERSION): docker/kustomize.version
 
 cache/%/helm-$(HELM_VERSION):
 	mkdir -p cache/$*
-	curl --fail -L -o cache/$*/helm-$(HELM_VERSION).tar.gz "https://storage.googleapis.com/kubernetes-helm/helm-v$(HELM_VERSION)-$*.tar.gz"
+	curl --fail -L -o cache/$*/helm-$(HELM_VERSION).tar.gz "https://get.helm.sh/helm-v$(HELM_VERSION)-$*.tar.gz"
 	tar -m -C ./cache -xzf cache/$*/helm-$(HELM_VERSION).tar.gz $*/helm
 	mv cache/$*/helm $@