title: github actions: how to check if current push has new tag (is new release)?
body: <pre><code>name: test-publish
  
  on: [push]
  
  jobs:
    test:
      strategy:
        ...
      steps:
        ...
  
    publish:
      needs: test
      if: github.event_name == 'push' &amp;&amp; github.ref???
      steps:
        ...  # eg: publish package to PyPI
  </code></pre>
  
  <p>What should I put in <code>jobs.publish.if</code> in order to check that this commit is new release?</p>
  
  <p>Is this okay: <code>contains(github.ref, '/tags/')</code>?</p>
  
  <p>What will happen if I push code and tag at the same time?</p>