Use current checkout action in workflows

Author: ripred

.github/workflows/python-app.yml

@@ -26,7 +26,7 @@ jobs:
 
     steps:
       - name: Checkout repository
-        uses: actions/checkout@v3
+        uses: actions/checkout@v6
 
       - name: Setup Python ${{ matrix.python-version }}
         uses: actions/setup-python@v4