AthAnalysisExternals: add flake8 packages
Add PyModules
and flake8_atlas
to the list of packages. We can then configure flake8 checking for the AthAnalysis project as well. Might be useful for those developers that develop code within that project to avoid warnings only showing up later in the CI.
Ideally, I would have liked adding it to AnalysisBase
as well but that's a bit more complicated as we cannot rely on pip
(taken from LCG) for installation.
cc @krumnack