Bump GitHub Actions to current majors

actions/checkout and actions/setup-python were on Node.js 20 majors,
which GitHub runners now flag as deprecated. No workflow logic changed.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

Author: DatafyingTech

.github/workflows/tests.yml

@@ -17,9 +17,9 @@ jobs:
         python-version: ["3.11", "3.12", "3.13"]
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v7
 
-      - uses: actions/setup-python@v5
+      - uses: actions/setup-python@v7
         with:
           python-version: ${{ matrix.python-version }}