using invalid format for service secrets misbehaves instead of failing

[SinnySupernova]

Describe the bug
using invalid format for service secrets doesn't fail, but misbehaves instead

Steps to reproduce the behavior

1. create a secret echo "aaa" | podman secret create test-secret -
2. create docker-compose.yml

services:
  tester:
    image: debian:trixie-slim
    command: "tail -f /dev/null"
    container_name: tester
    init: true
    secrets:
      test-secret: # this is not valid according to [docker compose spec](https://docs.docker.com/reference/compose-file/services/#secrets)
        source: test-secret
        type: env
        target: MY_VAR

secrets:
  test-secret:
    external: true

3. run docker compose up -d

Expected behavior
the command fails because services.tester.secrets in the docker compose file is invalid

Actual behavior
command runs, and the secret test-secret is mounted to /run/secrets/test-secret, but not as env variable

Output

$ podman-compose version
podman-compose version 1.5.0
podman version 5.7.0

Additional context

Reason for this is likely that dicts in python are enumerable and this line here
enumerates keys of secrets dict, which is incorrect behaviour here.