chore(deps): update postgres docker tag to v18.3 (#12)

This PR contains the following updates:

| Package | Update | Change |
|---|---|---|
| postgres | minor | `18.2-alpine` → `18.3-alpine` |

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Reviewed-on: #12
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docker-compose.yml

@@ -18,7 +18,7 @@ services:
         condition: service_healthy
 
   db:
-    image: postgres:18.2-alpine
+    image: postgres:18.3-alpine
     restart: unless-stopped
     environment:
       - POSTGRES_USER=documize