Add python 3.12 to tests

Author: davet2001

.github/workflows/ci.yml

@@ -7,7 +7,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.5", "3.6", "3.7", "3.8", "3.9", "3.10"]
+        python-version: ["3.5", "3.6", "3.7", "3.8", "3.9", "3.10", "3.12"]
     steps:
     - uses: actions/checkout@v2
     - name: Set up Python ${{ matrix.python-version }}