direnv configuration to support `layout poetry`

direnvrc

# ~/.config/direnv/direnvrc
# Adapted from https://rgoswami.me/posts/poetry-direnv/
layout_poetry() {
  if [[ ! -f pyproject.toml ]]; then
    log_error 'No pyproject.toml found. Use `poetry new` or `poetry init` to create one first.'
    exit 2
  fi

  # create venv if it doesn't exist
  poetry run true

  export VIRTUAL_ENV=$(poetry env info --path)
  export POETRY_ACTIVE=1
  PATH_add "$VIRTUAL_ENV/bin"
}