chore(deps): update actions/checkout action to v6 (#28)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/lint.yml

@@ -10,14 +10,14 @@ jobs:
   lint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: asdf-vm/actions/install@v3
       - run: scripts/lint.bash
 
   actionlint:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Check workflow files
         uses: docker://rhysd/actionlint:1.7.9
         with: