Fix build for AppVeyor

[hhtong]

No description provided.

[randomir]

Looks like the PATH fix works here as well.

But I would really, really, like to understand why these are showing:

C:\Python35\lib\site-packages\wheel\bdist_wheel.py:78: RuntimeWarning: Config variable 'Py_DEBUG' is unset, Python ABI tag may be incorrect
  warn=(impl == 'cp')):
C:\Python35\lib\site-packages\wheel\bdist_wheel.py:83: RuntimeWarning: Config variable 'WITH_PYMALLOC' is unset, Python ABI tag may be incorrect
  sys.version_info < (3, 8)))

AFAICT, it should be harmless. But it would be good to know for sure before we release a new version of Ocean.

Btw, appveyor utility files can now also be removed (see dwavesystems/qbsolv#152).

[boothby]

Is this only on Py3.5? That's in EOL, can we drop it now?

[arcondello]

@boothby, good point. Should we just be dropping 3.5 in Ocean generally? @randomir

dwavesystems/dwave-ocean-sdk#91

[randomir]

No, @boothby, it's on all versions.

@arcondello, sure, I don't mind dropping 3.5.

[randomir]

@hhtong, as long as you're fixing appveyor, can you also add tests for py38?

[hhtong]

@randomir Will do that right now. Should I also be removing the tests for 3.5 then? Or wait

[arcondello]

I would wait on 3.5, it's a bigger conversation.

[randomir]

@hhtong, I would wait with py35. It's not solving anything, and it's not in our way right now.