Switch to, configure ruff, fix lint

.github/workflows/ci.yml

.gitlab-ci.yml

doc/conf.py

doc/tutorial.rst

loopy/auto_test.py

loopy/cli.py

loopy/codegen/loop.py

loopy/diagnostic.py

loopy/frontend/fortran/__init__.py

loopy/frontend/fortran/translator.py

loopy/frontend/fortran/tree.py

loopy/kernel/array.py

loopy/kernel/data.py

loopy/kernel/tools.py

loopy/library/reduction.py

loopy/match.py

loopy/options.py

loopy/preprocess.py

loopy/statistics.py

loopy/symbolic.py