Update actions/checkout action to v4

Author: renovate[bot]

.github/workflows/gitleaks.yaml

@@ -6,7 +6,7 @@ jobs:
     name: gitleaks
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@692973e3d937129bcbf40652eb9f2f61becf3332 # v4
         with:
           fetch-depth: 0
       - uses: gitleaks/gitleaks-action@v2