Downgrade to Python 3.10: a venv made with -intel64 does not in fact …

…make an intel venv under 3.12, but it does under 3.10

.github/workflows/buildapp.yml

@@ -29,22 +29,19 @@ jobs:
 
       - name: Set up Python from python.org
         run: |
-          curl https://www.python.org/ftp/python/3.12.3/python-3.12.3-macos11.pkg --output python-installer.pkg
+          curl https://www.python.org/ftp/python/3.10.11/python-3.10.11-macos11.pkg --output python-installer.pkg
           sudo installer -pkg python-installer.pkg -target /
-
-          # Somehow using plain "python3" gives us the runner's homebrew Python,
-          # so let's be explicit about the path:
-          ourpython=/Library/Frameworks/Python.framework/Versions/3.12/bin/python3.12-intel64
-          ls -l $ourpython
-          $ourpython --version
-          $ourpython -c "import platform; print('platform:', platform.platform())"
-          $ourpython -c "import platform; print('macOS version:', platform.mac_ver()[0])"
-          $ourpython -m venv venv
+          python3.10-intel64 --version
+          python3.10-intel64 -c "import platform; print('macOS version:', platform.mac_ver()[0])"
+
+          which python3.10-intel64
+          python3.10-intel64 --version
+          python3.10-intel64 -c "import platform; print('platform:', platform.platform())"
+          python3.10-intel64 -c "import platform; print('macOS version:', platform.mac_ver()[0])"
+          python3.10-intel64 -m venv venv
           source venv/bin/activate
-          which python
-          python -c "import sys; print('\n'.join(sys.path))"
-          python --version
-          python -c "import platform; print('macOS version:', platform.mac_ver()[0], platform.platform())"
+          python -c "import platform; print('(venv) platform:', platform.platform())"
+          python -c "import platform; print('(venv) macOS version:', platform.mac_ver()[0])"
 
       - name: Install Dependencies
         run: |