chore(deps): update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/python-publish.yaml

@@ -13,7 +13,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Set up Python
         uses: actions/setup-python@v5
         with: