Improve Antora CI workflow by adding cache-dependency-path for npm step

Author: gpx1000

.github/workflows/build-antora-doc.yml

@@ -29,6 +29,7 @@ jobs:
         with:
           node-version: 'latest'
           cache: 'npm'
+          cache-dependency-path: './antora-ui-khronos/package-lock.json'
       - name: "Install dependencies"
         run: |
           sudo apt-get update