fix: Makefile: nightly build add bucket

Author: damdo

Makefile

@@ -119,6 +119,8 @@ REGISTRY ?= gcr.io/$(GCP_PROJECT)
 STAGING_REGISTRY := gcr.io/k8s-staging-cluster-api-gcp
 PROD_REGISTRY := registry.k8s.io/cluster-api-gcp
 IMAGE_NAME ?= cluster-api-gcp-controller
+STAGING_BUCKET ?= k8s-staging-cluster-api-gcp
+BUCKET ?= $(STAGING_BUCKET)
 export CONTROLLER_IMG ?= $(REGISTRY)/$(IMAGE_NAME)
 export TAG ?= dev
 export ARCH ?= amd64