chore(deps): update postgres:13.21 docker digest to b5a2a47 (rnaveiras#377)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| postgres | digest | `e119566` -> `b5a2a47` |

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Author: rnaveiras

compose.yaml

@@ -27,7 +27,7 @@ services:
     <<: *postgres
     # renovate: datasource=docker depName=postgres versioning=docker
     # renovate: allowedVersions=13.x
-    image: postgres:13.21@sha256:e1195666dc3edf6c8447bea6df9d7bccfdda66ab927d1f68b1b6e0cc2262c232
+    image: postgres:13.21@sha256:b5a2a475dec30df4835184909451b89e5a2e87d90e69e1c905ace8b941bbbdf4
     volumes:
       - postgres_data_13:/var/lib/postgresql/data
       - ./docker/postgresql.conf:/etc/postgresql/postgresql.conf