Pin macOS installer Sphinx to v2.0.1 (pythonGH-13774)

Author: ned-deily

Mac/BuildScript/build-installer.py

@@ -1058,6 +1058,7 @@ def buildPythonDocs():
     runCommand('make clean')
     # Create virtual environment for docs builds with blurb and sphinx
     runCommand('make venv')
+    runCommand('venv/bin/python3 -m pip install -U Sphinx==2.0.1')
     runCommand('make html PYTHON=venv/bin/python')
     os.chdir(curDir)
     if not os.path.exists(docdir):