Update postgres-exporter to 0.15.0, nginx to 1.25.3, postgresql12 to 12.16

This MR contains the following updates:

Package	Update	Change
registry1.dso.mil/ironbank/bitnami/postgres-exporter	minor	0.12.1 -> 0.15.0
registry1.dso.mil/ironbank/opensource/nginx/nginx	patch	1.25.2 -> 1.25.3
registry1.dso.mil/ironbank/opensource/postgres/postgresql12	minor	12.15 -> 12.16

---

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.