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

Author: renovate[bot]

.github/workflows/ci.yml

@@ -25,7 +25,7 @@ jobs:
           version: latest
           github-token: ${{ secrets.GITHUB_TOKEN }}
 
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Run build
         run: earthly --org ofalvai --sat homecooked --ci +build-all