Currently, GHA runs a CI suite that uses flake8 to check Python and lintr to check R.
Use "ruff check" to replace flake8 in CI, minimally running the current flake8 checks (E9,F63,F7,F82), but ideally doing more checks, without raising spurious errors. Also remove flake8 from the conda environments and add ruff instead.
Currently, GHA runs a CI suite that uses flake8 to check Python and lintr to check R.
Use "ruff check" to replace flake8 in CI, minimally running the current flake8 checks (E9,F63,F7,F82), but ideally doing more checks, without raising spurious errors. Also remove flake8 from the conda environments and add ruff instead.
Relates to #21.