In your workflow definition file, add the following step. This should be after you've deployed your site.
# .github/workflows/workflow.yml
jobs:
deployment_job:
...
steps:
...
- uses: dlehmann/google-ping-action@master
with:
sitemap-url: ${{ secrets.SITEMAP_URL }}https://docs.github.com/en/actions/creating-actions/creating-a-javascript-action