Update docker.io/postgres Docker tag to v17.6 (#1232)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| docker.io/postgres | minor | `17.5-alpine3.21` -> `17.6-alpine3.21` |

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### Configuration

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

♻ **Rebasing**: Whenever PR is behind base branch, or you tick the rebase/retry checkbox.

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

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 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

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Reviewed-on: #1232
Co-authored-by: Renovate Bot <renovate-bot@alexlebens.net>
Co-committed-by: Renovate Bot <renovate-bot@alexlebens.net>

hosts/ps10rp/gitea/compose.yaml

@@ -19,7 +19,7 @@ services:
             - /dev/net/tun:/dev/net/tun
 
     postgresql:
-        image: docker.io/postgres:17.5-alpine3.21
+        image: docker.io/postgres:17.6-alpine3.21
         container_name: gitea-postgres
         env_file:
             - .env