Promote v1.15.0 image

Author: amacaskill

registry.k8s.io/images/k8s-staging-cloud-provider-gcp/images.yaml

@@ -47,6 +47,7 @@
     "sha256:e3cda64a818864ddf5c63cf94a8a2509e88c44c2cb6cd3b2310e39f329c840dd": ["v1.13.6"]
     "sha256:eba3a897872087fff280edd390741817c98a1440ed83dc51c98012e22616c4d2": ["v1.13.7"]
     "sha256:289257e584b9114c1a1eaa2294d80ae57e8e130f9d47b6f8b49382cb09c248ac": ["v1.14.2"]
+    "sha256:ebf4d854ebf7dcff1d7d36fab160485d1f6196c5a1108416eafaa6b1b85c4f33": ["v1.15.0"]
     "sha256:23d2fe20c5307c3ef2580ed035084d9a57866717bd8b80bdc2dabd2097591227": ["v1.2.1"]
     "sha256:e9c355dd1ce57de91a0f9164bd2fe688938723e7f9bd40bb13652d603f41d25a": ["v1.2.2"]
     "sha256:7d20ed9af18c24b68b6afe715aeb539fd9c352af875d8329df4652bd0bc38ea8": ["v1.2.3"]