chore(ci): update checkout & setup-python versions

These were triggering warnings due to using an outdated version of Node.js
internally

.github/workflows/testing.yml

@@ -22,8 +22,10 @@ jobs:
           - 5432:5432
         options: --health-cmd pg_isready --health-interval 10s --health-timeout 5s --health-retries 5
     steps:
-      - uses: actions/checkout@v2
-      - uses: actions/setup-python@v2
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: 3.12
       - name: Install Dependencies
         run: |
           python -m pip install --upgrade pip