chore(deps): update postgres docker tag to v16 (#2588)

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This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| postgres | major | `11` -> `16` |

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.woodpecker/test.yml

@@ -136,7 +136,7 @@ steps:
 
 services:
   service-postgres:
-    image: postgres:11
+    image: postgres:16
     ports: ["5432"]
     environment:
       - POSTGRES_USER=postgres