Update CI configuration

"ubuntu-latest" no longer supports Python 3.7

Author: sde1000

.github/workflows/run-tests.yml

@@ -8,7 +8,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ['3.7', '3.8', '3.9', '3.10', '3.11']
+        python-version: ['3.8', '3.9', '3.10', '3.11', '3.12']
 
     steps:
       - uses: actions/checkout@v3