refactor(fixtures): support pytest>=8, drop pytest-cases dependency

[wpbonelli]

• pytest 8 sets request.session.name to the empty string where previously it was the pytest root workspace name, use request.config.rootpath.name instead
  • https://github.com/pytest-dev/pytest/releases/tag/8.0.0rc1
• drop pytest-cases optional dependency as it is unused and not yet supported by pytest 8
  • https://github.com/smarie/python-pytest-cases/issues/330