ci: add Python 3.14 in the unit test

Author: KazuCocoa

.github/workflows/unit-test.yml

@@ -12,7 +12,7 @@ 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:
     - uses: actions/checkout@v6
     - name: Set up Python ${{ matrix.python-version }}