Code clean up

[joachimmetz]

• remove # -*- coding: utf-8 -*-, which appears to be a PEP 263 remnant, and has been superseded by PEP 3120
• pylint enable super-with-arguments and useless-object-inheritance checks and change code accordingly
• Throw OSError instead of IOError - PEP 3151

consider using black, notable changes

• 4 space indentation
• line length 88
• strings are quotes with ", but if they contain a " string is quoted with '

consider using docformatter:

• currently conflicts with black, in regards to 2 empty lines between top level docstring and class definition (e.g. dfdatetime/factory.py)

consider switching to ruff

• remove pylint overrides