Set up Dockerfile

[afuetterer]

• Dockerfile
• .dockerignore
• multistage build
• env PYTHONUNBUFFERED
• env PYTHONDONTWRITEBYTECODE
• install python-re3data[cli]
• cmd or entrypoint re3data
• add test

FROM python:3.12-slim

Ref: https://github.com/search?q=%22from+python%3A3%22+build+wheel+%22copy+pyproject.toml%22+language%3ADockerfile&type=code