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

Author: renovate[bot]

.github/workflows/ci.yml

@@ -19,7 +19,7 @@ jobs:
         node: [20, 22, 24]
 
     steps:
-    - uses: actions/checkout@v5
+    - uses: actions/checkout@v6
     - name: Install pnpm
       uses: pnpm/[email protected]
     - name: Use Node.js ${{ matrix.node }}