Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/repo_linter.yaml

@@ -31,7 +31,7 @@ jobs:
         continue-on-error: true
 
       - name: Checkout repository
-        uses: actions/checkout@v4
+        uses: actions/checkout@v6
         with:
           path: main
           fetch-depth: "1"