BUG: AttributeError when read_sas used with GCS
With GCSFS (and when a binary file buffer is passed in), the output from
the file read is `bytes`, not a Unicode `str`. The `encode` call is unnecessary
in this case.

- [x] closes #33069 
- [x] tests added / passed
- [x] passes `black pandas`
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry

Not sure why "20.00% of diff hit (target 50.00%)", since I added a test and it's only one additional line of code. Maybe needs another test in text-mode?

Edit: None of the available XPT data files can be opened as a text file. It seems the `UnicodeEncodeError` passthrough may no longer be required at all with Python 3. @bashtage if you'd have a look. @tswast can you merge upstream master to resolve conflicts. Linting Thanks @tswast 