v0.4.0

feat

• Check files that should not exist (like .isort.cfg) (1901bb8)
• Check pre-commit config file and the presence of hooks (b1333db)
• Warn about replacing requirements.txt by pyproject.toml (dacb091)

fix

• Don't break when pyproject.toml or setup.cfg don't exist (6a546c1)
• Only check rules if the file exists (66e42d2)

refactor

• Check absence of pipenv files using the .toml config (4002015)
• Remove should_exist_default, consider existence of a config (8b22926)
• Use a mixin with a base error number for each class (bb7e73d)