Renovate: Upgrade Velero package dependencies

This MR contains the following updates:

Package	Update	Change
registry1.dso.mil/ironbank/opensource/kubernetes/kubectl	patch	v1.28.3 -> v1.28.4
velero/velero-plugin-for-aws	patch	v1.8.1 -> v1.8.2

---

Configuration

📅 Schedule: At any time (no schedule defined).

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

♻ Rebasing: Renovate will not automatically rebase this PR, because other commits have been found.

👻 Immortal: This MR will be recreated if closed unmerged. Get config help if that's undesired.

---

• If you want to rebase/retry this MR, click this checkbox.

---

This MR has been generated by Renovate Bot.