chore(ci): standardise poetry version to 1.8.3

What does this merge request do and why?

poetry has been upgraded to 1.8.3 in development as part of !800 (merged).

How to set up and validate locally

Numbered steps to set up and validate the change are strongly suggested.

Merge request checklist

• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.