futher improvement to macOS wheel names

[robbuckley]

see https://github.com/matthew-brett/multibuild/pull/242. This will remove more of the cruft from macOS wheel names, from:

pandas-0.25.0rc0-cp35-cp35m-macosx_10_6_intel.macosx_10_9_intel.macosx_10_9_x86_64.macosx_10_10_intel.macosx_10_10_x86_64.whl
pandas-0.25.0rc0-cp36-cp36m-macosx_10_9_x86_64.macosx_10_10_x86_64.whl
pandas-0.25.0rc0-cp37-cp37m-macosx_10_9_x86_64.macosx_10_10_x86_64.whl

to:

pandas-0.25.0rc0-cp35-cp35m-macosx_10_6_intel.whl
pandas-0.25.0rc0-cp36-cp36m-macosx_10_9_x86_64.whl
pandas-0.25.0rc0-cp37-cp37m-macosx_10_9_x86_64.whl

It will mean updating the multibuild module again. Is there still time to do this before 0.25?

[jreback]

0.25 is released but this like a good change and we can incorporate into the next release