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

Author: renovate[bot]

.github/workflows/ci.yml

@@ -5,7 +5,7 @@ jobs:
     runs-on: ubuntu-24.04
 
     steps:
-      - uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5
+      - uses: actions/checkout@df4cb1c069e1874edd31b4311f1884172cec0e10 # v6
 
       - name: Set up Python
         uses: actions/setup-python@83679a892e2d95755f2dac6acb0bfd1e9ac5d548 # v6