Settup Github CI/CD with unit tests, mypy and linting checks

[mlemayTTE]

This PR is about updating GitHub CI (following initial settup #4) to include testing, linting and type checking since more Python code will be push from various teams following #54.

I propose to add:

• testing with pytest, pytest-cov
• type checking with mypy
• linting. I am used to work with ruff, but the current python-package.yml include yapf. Does anyone have preferences?

Some open questions:

• Do all the existing packages conform to typing and linting rules? What is the strategy if they do not (refactoring them before merging the PR, or removing them from checking and refactoring them later)?
• What are Python versions supported? Is py3.8 still usefull?

[untereiner]

Following the official python versions roadmap :

• python3.8 is behond end-of-life
• python3.9 is very soon end-of-life

From where I stand I would suggest:

• a table to identify the different systems in use among the partners and their possible python versions
• update to an - as close as possible to the latest bufix or feature - version of python

[mlemayTTE]

Shall all the packages be based on the same Python version ?
Because the future geos-pv package that will contain Paraview plugins must be compliant with Paraview Python version (https://www.kitware.com/using-python-virtual-environments-in-paraview-5-13-0/).
Paraview Python versions are currently 3.9 for PV < 5.12, and 3.10 for PV >=5.12 (https://www.paraview.org/download/). So geos-pv package at least must be based on Python 3.9 and/or 3.10.

[untereiner]

3.10 is a good starting point until next year.