chore: update actions/checkout and actions/setup-python to v6 in testing workflow

Author: ceccopierangiolieugenio

.github/workflows/testing.yml

@@ -45,10 +45,10 @@ jobs:
         python-version: ['3.9', '3.10', '3.11', '3.12', '3.13', '3.14']
 
     steps:
-    - uses: actions/checkout@v3
+    - uses: actions/checkout@v6
 
     - name: Set up Python ${{ matrix.python-version }}
-      uses: actions/setup-python@v3
+      uses: actions/setup-python@v6
       with:
         python-version: ${{ matrix.python-version }}