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

Author: renovate[bot]

.github/workflows/renovate-config-check.yaml

@@ -12,7 +12,7 @@ jobs:
   validate:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6
 
       - name: Validate renovate.json
         run: npx --yes --package renovate -- renovate-config-validator