Bump Sphinx to 2.2.0. (GH-16532)

diff --git a/Mac/BuildScript/build-installer.py b/Mac/BuildScript/build-installer.py
index 0dd5364..3d1381b 100755
--- a/Mac/BuildScript/build-installer.py
+++ b/Mac/BuildScript/build-installer.py
@@ -1068,7 +1068,7 @@
     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('venv/bin/python3 -m pip install -U Sphinx==2.2.0')
     runCommand('make html PYTHON=venv/bin/python')
     os.chdir(curDir)
     if not os.path.exists(docdir):