Add Flake8 linting in 2018-patches, targetting only Phys/StrippingConf for now
More work towards DPA task https://gitlab.cern.ch/lhcb-dpa/project/-/issues/246.
This gets us started with Flake8
checks. I started small, only targetting the Phys/StrippingConf directory for now, given the work (=pain) this meant already. If we get things nice and clean for core/central pieces of Stripping we can then ask liaisons and committers to have their commits comply with Flake8
:-).