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

Author: renovate[bot]

.github/workflows/main.yaml

@@ -16,7 +16,7 @@ jobs:
     name: Test
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Use Node.js 24.x
         uses: actions/setup-node@v6
         with:
@@ -38,7 +38,7 @@ jobs:
     needs: test
     if: github.ref == 'refs/heads/main'
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - name: Use Node.js 24.x
         uses: actions/setup-node@v6
         with: