title: Slack bot fails to send message to restricted general channel via chat.postMessage
body: <p>This is my first time trying to create a slack bot and I am following this <a href="https://github.com/slackapi/template-announcement-approvals" rel="noreferrer">template code</a> to the word, I have not made any changes, and just remixed on glitch, copy-pasted the auth tokens correctly, things worked just fine.
  That is until I made the #general channel restricted for <code>Full Member</code> users.</p>
  
  <p>This is the error I see in the logs at glitch.</p>
  
  <p><code>PostMessage Error: restricted_action</code></p>
  
  <p>Is there an additional scope that I need to set, other than <code>bot</code> ?<a href="https://i.stack.imgur.com/Hs338.png" rel="noreferrer"><img src="https://i.stack.imgur.com/Hs338.png" alt="enter image description here"></a></p>
  
  <p>Here is the workspace user permissions, I am the owner for this workspace.
  <a href="https://i.stack.imgur.com/tMljE.jpg" rel="noreferrer"><img src="https://i.stack.imgur.com/tMljE.jpg" alt="Workspace User Permissions"></a></p>
  
  <p>Here is the code:</p>
  
  <pre><code>const postAnnouncementToChannel = (user, announcement) =&gt; {
    const { title, details, channel } = announcement;
  
    let announcementData = {
      token: process.env.SLACK_ACCESS_TOKEN,
      channel: channel,
      text: `:loudspeaker: Announcement from: &lt;@${user}&gt;`,
      attachments: JSON.stringify([
        {
          title: title,
          text: details,
          footer: 'DM me to make announcements.'
        }
      ])
    };
    send(announcementData, user);
  }
  
  
  const send = async(data) =&gt; { 
    data.as_user = true; // send DM as a bot, not Slackbot
    const result = await axios.post(`${apiUrl}/chat.postMessage`, qs.stringify(data))
    try {
      if(result.data.error) console.log(`PostMessage Error: ${result.data.error}`);
    } catch(err) {
      console.log(err);
    }
  }
  </code></pre>
  
  <p>Testing it via </p>
  
  <p><a href="https://api.slack.com/methods/chat.postMessage/test" rel="noreferrer">https://api.slack.com/methods/chat.postMessage/test</a>
  using bot-token says </p>
  
  <pre><code>{
      "ok": false,
      "error": "restricted_action"
  }
  </code></pre>
  
  <p>Testing this using xoxp-token gives this:-</p>
  
  <pre><code>{
      "ok": false,
      "error": "missing_scope",
      "needed": "chat:write:user",
      "provided": "identify,bot"
  }
  </code></pre>