Regressions are not cool, but it was a deliberate choice to not support
bytes filenames in os.scandir(). If you use bytes, you can get filenames
which are invalid: you will be unable to use the filename with open() to
read its content for example.

Bytes filename are deprecated since python 3.2 if i recall correctly. It's
time to use the right time, it's also simpler to use on Python 3.

I suggest to document the regression rather than adding bytes support to
os.scandir or don't use scandir in os.walk().