Here’s my config for reference, which works for me:

name: forgejo
services:
  forgejo:
    image: codeberg.org/forgejo/forgejo:12
    environment:
      - USER_UID=1000
      - USER_GID=1000
    restart: always
    volumes:
      - ./data:/data
      - /etc/timezone:/etc/timezone:ro
      - /etc/localtime:/etc/localtime:ro
    ports:
      - 80:3000
      - 2222:22

If you can share your error message we might be able to better pinpoint the issue.