Improve file paths using Path instead of str

[lchoquel]

Before submitting

• I've checked open issues and found no similar item
• It's not really a bug report or a feature request

What would you like to discuss or change?

We want to use modern best practices wherever we can (while remaining compatible with python ≥ 3.10).
One of these best practices is to use from pathlib import Path insead of treating file paths as strings.

Relevant context (optional)

No response

Would you like to help drive or implement this?

None