ci: test full github url for checkout action

.gitea/workflows/services-docs-next-required.yml

@@ -25,7 +25,7 @@ jobs:
     runs-on: apex-debian13
     steps:
     - name: Checkout repository
-      uses: actions/checkout@v4
+      uses: https://github.com/actions/checkout@v4
       with:
         submodules: recursive
     - name: Setup Hugo