Merge pull request #1063 from justaugustus/kube-cross

build-image: Promote kube-cross:v1.15.0-rc.1-1

Author: k8s-ci-robot

k8s.gcr.io/images/k8s-staging-build-image/images.yaml

@@ -100,6 +100,7 @@
     "sha256:8d3fd0e3e126b085d4475f1954cc394a2ebea908f370095eb7463d2b1f4dbfdd": ["v1.12.17-1"]
     "sha256:95366bfc21a10198b6f0ece3e0dcac27d9b8e39fc69239aa62d76b4a2b5ca261": ["v1.13.9-2"]
     "sha256:97e77164ddc1f9ab56bcbab3e2895b882097b1eabd820497e894f41c0e4908fe": ["v1.12.12-1"]
+    "sha256:a20a0d599c27ad3f79258efdf22dd865505ef1615ebe42c806016e40b7e1e301": ["v1.15.0-rc.1-1"]
     "sha256:a297fddaaa8f8e88620de1f94c44dbbf26aaaf5f256266bf5c7eca5f0f68f56d": ["v1.14.4-2"]
     "sha256:b33ada5ba9b267ab9fc77b18aa9ceebc51ced6c57fb262eecb2d5ac35a3cfa52": ["v1.13.12-2"]
     "sha256:ba9be5f16f12bd166614d5179f794fc7bd715df71b5d5cdb1c4f7768ecad1d5c": ["v1.13.13-2"]