ci: test with Python 3.14

Author: vlaci

.github/workflows/CI.yml

@@ -81,7 +81,7 @@ jobs:
     runs-on: ubuntu-latest
     strategy:
       matrix:
-        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13"]
+        python-version: ["3.9", "3.10", "3.11", "3.12", "3.13", "3.14"]
     steps:
       - name: Checkout source code
         uses: actions/checkout@v4