CI: Add job for testing Python 3.13

Author: martinRenou

Diff for: .github/workflows/main.yml

@@ -20,7 +20,7 @@ jobs:
       fail-fast: false
       matrix:
         os: [ubuntu-latest, macos-latest, windows-latest]
-        python-version: ["3.7", "3.9", "3.11", "3.12"]
+        python-version: ["3.7", "3.8", "3.9", "3.11", "3.12", "3.13"]
 
     steps:
     - uses: actions/checkout@v4