Upgrade Python packages to their latest version when using poetry

Poetry currently¹ lacks a command to upgrade all dependencies (packages declared in pyproject.toml ) to their latest available versions in one go (you can do it for individual packages using poetry add package@latest).

This is tracked in python-poetry/poetry#461.

Until this is implemented natively in poetry itself, users can use poetryup as a workaround:

poetry add --dev poetryup
poetryup --latest