Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/ci.yml

@@ -5,7 +5,7 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/cache@v4
         with:
           path: '**/node_modules'
@@ -33,7 +33,7 @@ jobs:
       - name: Ensure line endings are consistent
         run: git config --global core.autocrlf input
       - name: Check out repository
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
       - uses: actions/cache@v4
         with:
           path: '**/node_modules'