Update actions/checkout to v6

Author: tniessen

.github/workflows/deploy.yml

@@ -10,7 +10,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       - name: Checkout
-        uses: actions/checkout@v5
+        uses: actions/checkout@v6
         with:
           submodules: recursive
       - name: Install wasi-sdk