Dockerfile: update to Fedora 39

[c4rt0]

See: coreos/fedora-coreos-tracker#1490

[jlebon]

To roll this out, see https://docs.fedoraproject.org/en-US/infra/sysadmin_guide/coreos-cincinnati/#_upgrades.

[c4rt0]

PR with the update to the fedora-infra/ansible repository

[c4rt0]

To roll this out, see https://docs.fedoraproject.org/en-US/infra/sysadmin_guide/coreos-cincinnati/#_upgrades.

The build stage of the Upgrade is now complete.

[c4rt0]

@jlebon - how do I verify that the target commit has been successfully built into a container image?

[jlebon]

You can log into the OpenShift instance, switch to the coreos-cincinnati project (oc project ...), and then inspect the build that was triggered (oc get builds, oc logs build/...) and verify that the pod is up and happy (oc get pods, oc logs ...).