ci: disable python 3.11 tests on mac os while that's not available

Related: actions/runner-images#6459
Related: actions/setup-python#531

.github/workflows/test-from-sources.yml

@@ -17,13 +17,14 @@ jobs:
         python-version: ['3.11', '3.10', '3.9', '3.8', '3.7']
         os: [ubuntu-latest, macos-latest, windows-latest]
         exclude:
-          # mac os: exclude all but the last two python releases
-          - os: macos-latest
-            python-version: 3.9
+          # mac os: exclude all but the last two (available) python releases
           - os: macos-latest
             python-version: 3.8
           - os: macos-latest
             python-version: 3.7
+          # mac os: exclude python 3.11 since it's not yet available for runners
+          - os: macos-latest
+            python-version: 3.11
           # windows: exclude all but the last two python releases
           - os: windows-latest
             python-version: 3.9