Update data-platform-workflows to v19

[renovate[bot]]

This PR contains the following updates:

Package	Type	Update	Change
canonical/data-platform-workflows	action	major	v18 -> v19
canonical/data-platform-workflows	action	major	v18.0.0 -> v19.0.0

---

Release Notes

canonical/data-platform-workflows (canonical/data-platform-workflows)

### [`v19`](https://togithub.com/canonical/data-platform-workflows/compare/v18...v19) [Compare Source](https://togithub.com/canonical/data-platform-workflows/compare/v18...v19)

---

Configuration

📅 Schedule: Branch creation - "after 1am and before 3am every weekday" in timezone Etc/UTC, Automerge - At any time (no schedule defined).

🚦 Automerge: Disabled by config. Please merge this manually once you are satisfied.

♻ Rebasing: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 Ignore: Close this PR and you won't be reminded about these updates again.

---

• [ ] If you want to rebase/retry this PR, check this box

---

This PR was generated by Mend Renovate. View the repository job log.