CI: Test Python 3.13, drop support for Python 3.8

Author: adrienverge

.github/workflows/tests.yaml

@@ -29,11 +29,11 @@ jobs:
     strategy:
       matrix:
         python-version:
-          - '3.8'
           - '3.9'
           - '3.10'
           - '3.11'
           - '3.12'
+          - '3.13'
     steps:
       - name: Checkout
         uses: actions/checkout@v4