fix issues caught by flake8 and add CI job to run linter
Adds job to run flake8 against the sources to catch PEP 8 violations and other coding errors.
Fixed all issues already caught by flake8 (minus a few that have been explicitly ignored).
[A venir] Mise en place de quotas sur nos instances GitLab. Plus d'information sur : https://doc-si.inria.fr/pages/viewpage.action?pageId=129728565
[Coming soon] Quotas installation on our GitLab instances. More information: https://doc-si.inria.fr/pages/viewpage.action?pageId=129728565
Adds job to run flake8 against the sources to catch PEP 8 violations and other coding errors.
Fixed all issues already caught by flake8 (minus a few that have been explicitly ignored).