Update pypi publishing

[f-hafner]

Description

• [x] I have read the contribution guidelines
• [x] This update is in line with what is recommended in the Python chapter of the Guide

This proposes a fix to #372.

I just now realise #373 asks for a workflow. I had also wondered whether I should add that. For now, it's just in the sample code in the README.dev.md file. I can transfer this into a workflow file -- can you give some feedback on the sample code? I copied from a workflow that works, but perhaps you have suggestions for improvement.