I'm trying ruff but when I do ruff check . on my example: print("%s" % "hello") it shows: UP031 Use format specifiers instead of percent format and if I do ruff check . --fix or ruff format . they don't change anything. My pyproject.toml snipped: [tool.ruff] target-version = "py39" line-length = 120 extend-select = ["E501", "UP", "RUF"] Continue reading...