Resolved auditwheel error by further pinning of wheel to 0.31.1

[radarhere]

I have found new errors generated on Linux by the upgrade to wheel 0.32, so this is a sequel to #100.

https://travis-ci.org/python-pillow/pillow-wheels/jobs/435427307#L4860

Traceback (most recent call last):
  File "/usr/local/bin/auditwheel", line 11, in <module>
    sys.exit(main())
  File "/opt/_internal/cpython-3.6.6/lib/python3.6/site-packages/auditwheel/main.py", line 49, in main
    rval = args.func(args, p)
  File "/opt/_internal/cpython-3.6.6/lib/python3.6/site-packages/auditwheel/main_repair.py", line 43, in execute
    from .repair import repair_wheel
  File "/opt/_internal/cpython-3.6.6/lib/python3.6/site-packages/auditwheel/repair.py", line 13, in <module>
    from .wheeltools import InWheelCtx, add_platforms
  File "/opt/_internal/cpython-3.6.6/lib/python3.6/site-packages/auditwheel/wheeltools.py", line 14, in <module>
    from wheel.util import urlsafe_b64encode, open_for_csv, native  # type: ignore
ImportError: cannot import name 'open_for_csv'

auditwheel uses Python 3, so I've pinned the wheel for Python 3 using another custom function.

[hugovk]

Great timing :)

I've reported this upstream: pypa/auditwheel#102.