Ensure docker-compose.yml works with Podman Compose

Resolves the following error:

Error: short-name "postgres:15.5" did not resolve to an alias and no
unqualified-search registries are defined in
"/etc/containers/registries.conf"

docker-compose.yml

@@ -1,6 +1,6 @@
 services:
   postgres:
-    image: postgres:15.5
+    image: docker.io/postgres:15.5
     volumes:
       - postgres-data:/var/lib/postgresql/data
     environment: