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

Author: renovate[bot]

.github/workflows/publish.yml

@@ -17,7 +17,7 @@ jobs:
     timeout-minutes: 30
 
     steps:
-      - uses: actions/checkout@v4
+      - uses: actions/checkout@v6
 
       - name: Log in to GHCR
         uses: docker/login-action@v3