title: How to add pass a env variable as part of a json in Github Actions?
body: <p>I have the following steps as part of a Github Workflow:</p>
  <pre><code>run: |
      MESSAGE=&quot;${{ env.MESSAGE }}&quot; &amp;&amp; echo $MESSAGE \ &amp;&amp;
      curl -X POST -H 'Content-type: application/json' --data '{&quot;text&quot;:$MESSAGE}' https://hooks.slack.com/services/&lt;some_ids&gt;
  </code></pre>
  <p>The echo works and outputs the correct message, but replacing the message in the json fails. What is the correct syntax?</p>
  <p>I already tried escaping the quotes (it's not valid syntax):</p>
  <pre><code>--data '{&quot;text&quot;:\&quot;$MESSAGE\&quot;}' 
  </code></pre>