`--keep-files` doesn't actually work

[fireattack]

Describe the bug
--keep-files flag doesn't work, at least not in a way I expected (there is no description; but I assume it means to keep all the temp files).

From the code:

        finally:
            if not args.keep_files and os.path.exists(twspace_dl.tempdir.name):
                twspace_dl.tempdir.cleanup()

It is supposed to only cleanup() if not args.keep_files, but twspace_dl.tempdir is going to automatically clean itself either way due to the nature of how TemporaryDirectory works.

To Reproduce
python -m twspace_dl -U XXX --keep-files

Expected behavior
A clear and concise description of what you expected to happen.

Desktop (please complete the following information):

• OS: Windows, python 3.8
• Version master
• Installation method (binary, pip, or other) source

[Ryu1845]

Ah yes I should use mkdtemp probably