Automate version bump

[georgethebeatle]

Background

Currently we have a slack reminder that prompts us to bump the API version that we return on GET /:

Reminder: Have you looked into bumping the v3 API Version in the Korifi API? Example: https://github.com/cloudfoundry/korifi/pull/1205

Provided that we do not cover the complete CF API specification, it does not make sense to inspect each and every specification release to decide whetehr we support it or not. On the other hand, we need to keep the version we return in sync with the versions supported by the cf cli.

Can we automate the process via:

• Introduce a job that runs once weekly that PRs bumping the API version
• Make smoke tests ensure that the cf cli does not complain about that version
• Ensure smoke tests are run with latest cf cli (i.e. do not use cf from the ci-image, maybe always install latest)