Update checkout action to v6 in publish workflow

Bumps the jonobr1/checkout action from v5 to v6 in the GitHub Actions publish workflow for improved stability and latest features.

Author: jonobr1

.github/workflows/publish.yml

@@ -13,8 +13,8 @@ jobs:
   publish:
     runs-on: ubuntu-latest
     steps:
-      # checkout@v5
-      - uses: jonobr1/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8
+      # checkout@v6
+      - uses: jonobr1/checkout@8e8c483db84b4bee98b60c0593521ed34d9990e8
       # setup-node@v6
       - uses: jonobr1/setup-node@395ad3262231945c25e8478fd5baf05154b1d79f
         with: