chore(deps): update container image rancher/system-upgrade-controller to v0.15.1

Signed-off-by: Nicholas Wilde <ncwilde43@gmail.com>

Author: renovate[bot]

cluster/core/operators/system-upgrade/deployment.yaml

@@ -66,7 +66,7 @@ spec:
           envFrom:
             - configMapRef:
                 name: default-controller-env
-          image: rancher/system-upgrade-controller:v0.7.6
+          image: rancher/system-upgrade-controller:v0.15.1
           imagePullPolicy: IfNotPresent
           name: system-upgrade-controller
           volumeMounts: