chore(deps): update actions/setup-python action to v6

Author: renovate[bot]

.github/workflows/backup.yml

@@ -17,7 +17,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version-file: '.python-version'
 

.github/workflows/ruff.yml

@@ -20,7 +20,7 @@ jobs:
         uses: actions/checkout@v6
 
       - name: Set up Python
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v6
         with:
           python-version-file: '.python-version'