Update actions/checkout action to v6

Author: renovate[bot]

.github/workflows/foundry-npm.yml

@@ -6,7 +6,7 @@ jobs:
     test_foundry_npm:
         runs-on: ubuntu-latest
         steps:
-            - uses: actions/checkout@v4
+            - uses: actions/checkout@v6
             - uses: actions/setup-node@v4
               with:
                   node-version: 16