Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/main.yml

@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-22.04
     timeout-minutes: 120
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Setup Node.js environment
         uses: actions/setup-node@v4.4.0
         with:
@@ -83,7 +83,7 @@ jobs:
     runs-on: ubuntu-22.04
     timeout-minutes: 60
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - name: Setup Node.js environment
         uses: actions/setup-node@v4.4.0
         with: