Github action to rebuild web pages not working

I think I have a basic confusion about GitHub Actions. I think it has to do with artifacts which I don’t understand. I have a very simple action script to run a python program and then regenerate GitHub Pages that incorporate some images that the python has generated. It seems to work except that the gh pages are not updated. It is as if the generated files are lost when the action is over. Here’s my code:

# This workflow will install Python dependencies, run tests and lint with a single version of Python
# For more information see: https://help.github.com/actions/language-and-framework-guides/using-python-with-github-actions

name: covid-page-update
on:
  push:
    branches: [ master ]
  schedule:
    - cron: 0 * * * *

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/setup-ruby@v1
      with:
        ruby-version: '2.6' # Version range or exact version of a Ruby version to use, using semvers version range syntax.
    - name: Set up Python 3.8
      uses: actions/setup-python@v1
      with:
        python-version: 3.8
    - uses: actions/checkout@v2
      with:
        fetch-depth: 0
    - name: Dependencies
      run: |
        pip install pandas
        pip install matplotlib
        pip install seaborn
    - name: What files are there now
      run: ls -la; pwd
    - name: Run daily
      run: erb index.erb.html > index.html
    - name: What files are there now
      run: ls -la; pwd
    - uses: peaceiris/actions-gh-pages@v3
      with:
        github_token: ${{ secrets.GITHUB_TOKEN }}
        publish_dir: .
    - name: Push changes
      uses: ad-m/github-push-action@master
      with:
        github_token: ${{ secrets.GITHUB_TOKEN }}
        branch: ${{ github.ref }}