CI: special case Python 3.11

Author: mr-c

.github/workflows/ci-tests.yml

@@ -35,10 +35,18 @@ jobs:
       - uses: actions/checkout@v3
 
       - name: Set up Python
+        if: matrix.py-ver-minor != 11
         uses: actions/setup-python@v4
         with:
           python-version: ${{ env.py-semver }}
 
+      - name: Set up Python 3.11.0-rc.1
+        if: matrix.py-ver-minor == 11
+        uses: actions/setup-python@v4
+        with:
+          python-version: 3.11.0-rc.1
+
+
       - name: Cache for pip
         uses: actions/cache@v3
         with: