name: Publish to RubyGems.org
on:
  push:
    tags:
      - '*'
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Set up Ruby
      uses: eregon/use-ruby-action@master
      with:
        ruby-version: 2.7
    - name: Publish to RubyGems.org
      uses: cadwallion/publish-rubygems-action@master
      env:
        GITHUB_TOKEN: ${{secrets.GITHUB_TOKEN}}
        RUBYGEMS_API_KEY: ${{secrets.RUBYGEMS_API_KEY}}

name: Publish to RubyGems.org
on:
  push:
    tags:
      - '*'
jobs:
  build:
    runs-on: ubuntu-latest
    steps:
    - uses: actions/checkout@v2
    - name: Set up Ruby
      uses: eregon/use-ruby-action@master
      with:
        ruby-version: 2.7
    - name: Publish to RubyGems.org
      run: |
        mkdir -p $HOME/.gem
        touch $HOME/.gem/credentials
        chmod 0600 $HOME/.gem/credentials
        printf -- "---\n:rubygems_api_key: ${RUBYGEMS_API_KEY}\n" > $HOME/.gem/credentials
        gem build *.gemspec
        gem push *.gem
      env:
        RUBYGEMS_API_KEY: ${{secrets.RUBYGEMS_API_KEY}}

Replace cadwallion/publish-rubygems-action with manual call of `gem push`
Replace cadwallion/publish-rubygems-action with manual call of `gem push`

Turns out, cadwallion/publish-rubygems-action doesn't work:
https://github.com/asciidoctor/asciidoctor-epub3/commit/f5f74c7fa783bf6b50031394592bec335cef5fb9/checks?check_suite_id=410741589#step:5:6

In the future, this manual step could be replaced with a different action (if one exists).
