[ci] Update actions/checkout action to v6

Author: lpinca

.github/workflows/ci.yml

@@ -47,7 +47,7 @@ jobs:
             node: 22
             os: windows-latest
     steps:
-      - uses: actions/checkout@v5
+      - uses: actions/checkout@v6
       - uses: actions/setup-node@v6
         with:
           node-version: ${{ matrix.node }}