Preinstall pathlib on macOS

scripts/osx-setup.sh

@@ -3,6 +3,8 @@ echo "Python version:"
 python3 --version
 echo "Upgrading pip..."
 python3 -m pip install --upgrade pip
+echo "Installing pathlib2 (wxpython issue workaround)..."
+python3 -m pip install pathlib2
 echo "Installing app requirements..."
 python3 -m pip install -r requirements.txt
 echo "Installing packaging tools..."