Let makedirs accept `exist_ok` as argument and fix default behavior

[ftputiluser]

thank you for this library.

to fit the pyhton os module it would be nice if makedirs could accept additional args.

[schwa]

Thank you for the report!

I agree, FTPHost.makedirs should accept the exist_ok argument, as os.makedirs does.

When looking at the code, I noticed that the current implementation doesn't accept an exist_ok argument, but behaves as if exist_ok=True was given. However, according to the documentation at ​https://docs.python.org/3/library/os.html#os.makedirs , exist_ok should be False by default.

I plan to change the behavior in a future ftputil 4.0.0, so that makedirs without exist_ok conforms to the Python documentation and the exist_ok argument is supported.