Lint fixes and enhancements

[jbaptperez]

A couple of modifications:

1. Fixes lint issues:
   1. flake8,
   2. pylint (factorizes duplicated code into a pytests/common.py file),
2. Fixes CONTRIBUTING.md:
   1. Typos,
   2. Updates URL of signing request documentation (--signoff instead of --gpg-sign),
   3. Formats Markdown.

Lint fixing commits are independents.

As I added the pytests/common.py source file to factorise some duplicated code, the pre-commit run --all-files command starts require an initial call to export PYTHONPATH=$PWD where $PWD is the root directory of the repository.

Is really # pylint: disable=import-error a correct way to handle this kind of issue?
I did not find a proper and portable way to solve this problem directly in .pylintrc, but I'm open to suggestions.

[p12tic]

Thanks for the PR.

In the documentation, please keep line length to around 100 chars or less.

The unit tests have migrated from pylint to unittest, so these changes are probably no longer relevant.

I understand a lot of time have passed, so you probably won't have time to go back to the PR. Maybe someone else can use the review to help extract useful stuff from the PR.

[jbaptperez]

@p12tic

Thanks for the PR.

In the documentation, please keep line length to around 100 chars or less.

Done.

The unit tests have migrated from pylint to unittest, so these changes are probably no longer relevant.

I understand a lot of time have passed, so you probably won't have time to go back to the PR. Maybe someone else can use the review to help extract useful stuff from the PR.

I removed outdated fixes, rebased my branch onto main and updated the PR.

However, the pytest to unitest and ruff migrations look not to be completed and I think README.md and CONTRIBUTING.md (or even setup.py) have to be updated accordingly.

[p12tic]

However, the pytest to unitest and ruff migrations look not to be completed and I think README.md and CONTRIBUTING.md (or even setup.py) have to be updated accordingly.

Thanks, indeed..