PYTHON-2403 Add macOS Python 3.9 release automation

[ShaneHarvey]

Patch: https://evergreen.mongodb.com/version/5fa5ac2f0305b945939ab269

[ShaneHarvey]

It seems that virtualenv is non functional with the current 3.9 install:

 [2020/11/06 20:11:38.052] + VIRTUALENV='/usr/local/bin/virtualenv -p /Library/Frameworks/Python.framework/Versions/3.9/bin/python3'
 [2020/11/06 20:11:38.052] + /usr/local/bin/virtualenv -p /Library/Frameworks/Python.framework/Versions/3.9/bin/python3 --system-site-packages --never-download venvtestinstall
 [2020/11/06 20:11:38.148] /usr/local/lib/python2.7/site-packages/virtualenv.py:1047: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
 [2020/11/06 20:11:38.148]   import imp
 [2020/11/06 20:11:38.213] removing build/bdist.macosx-10.9-x86_64/wheel
 [2020/11/06 20:11:38.213] /usr/local/bin/virtualenv
 [2020/11/06 20:11:38.213] Using base prefix '/Library/Frameworks/Python.framework/Versions/3.9'
 [2020/11/06 20:11:38.213] New python executable in /data/mci/87e4d98327ee9dcbc92d3124af4cb34c/src/venvtestinstall/bin/python3
 [2020/11/06 20:11:38.213] Also creating executable in /data/mci/87e4d98327ee9dcbc92d3124af4cb34c/src/venvtestinstall/bin/python
 [2020/11/06 20:11:38.213] ERROR: The executable /data/mci/87e4d98327ee9dcbc92d3124af4cb34c/src/venvtestinstall/bin/python3 is not functioning
 [2020/11/06 20:11:38.213] ERROR: It thinks sys.prefix is '/Library/Frameworks/Python.framework/Versions/3.9' (should be '/data/mci/87e4d98327ee9dcbc92d3124af4cb34c/src/venvtestinstall')
 [2020/11/06 20:11:38.213] ERROR: virtualenv is not compatible with this system or executable
 [2020/11/06 20:11:38.219] Running virtualenv with interpreter /Library/Frameworks/Python.framework/Versions/3.9/bin/python3
 [2020/11/06 20:11:38.223] Command failed: command encountered problem: error waiting on process '67f25ebb-d689-44c9-aa2b-1f4c60e9c667': exit status 100
 [2020/11/06 20:11:38.223] Task completed - FAILURE.

I'll file this issue with the build team.

[prashantmital]

Looks like the 10.14 hosts now have virtualenv installed. I think you can try running the build again to see if it works @ShaneHarvey

[ShaneHarvey]

Alright, this is working now, patch: https://evergreen.mongodb.com/version/5fa5ac2f0305b945939ab269