Renovate: Update postgres Dockerfile base image (#932)

This PR contains the following updates:

| Package | Type | Update | Change |
|---|---|---|---|
| debian |  | digest | `b6e2a15` → `4e401d9` |
| debian | final | digest | `b6e2a15` → `4e401d9` |

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postgres/Dockerfile

@@ -1,4 +1,4 @@
-FROM debian:trixie-slim@sha256:b6e2a152f22a40ff69d92cb397223c906017e1391a73c952b588e51af8883bf8
+FROM debian:trixie-slim@sha256:4e401d95de7083948053197a9c3913343cd06b706bf15eb6a0c3ccd26f436a0e
 
 # explicitly set user/group IDs
 RUN set -eux; \