install setuptools, no longer available by default in python 3.12

.github/workflows/runtests.yml

@@ -20,7 +20,7 @@ jobs:
         run: |
           python -m pip install --upgrade pip
           pip install -r requirements.txt
-          pip install pycodestyle pyflakes pylint dlint pyupgrade
+          pip install pycodestyle pyflakes pylint dlint pyupgrade setuptools
       - name: Run tests
         env:
           RUN_ONLINETESTS: 1