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

Author: renovate[bot]

.github/workflows/CI.yml

@@ -15,7 +15,7 @@ jobs:
         os:
           - ubuntu-latest
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
       - uses: pnpm/action-setup@v4
       - uses: actions/setup-node@v4
         with: