Experimentally add Python 3.13

Author: insolor

.github/workflows/python-tests.yml

@@ -23,7 +23,7 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
-        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12"]
+        python-version: ["3.8", "3.9", "3.10", "3.11", "3.12", "3.13-dev"]
 
     steps:
     - uses: actions/checkout@v4