ci: fix slackapi v2.1.1 (#389)

This PR tries to properly migrate from v1.25.0 to v2.1.1.

Previous attempt #384
got reverted.

Author: maksymar

.github/workflows/ci-notify-slack.yml

@@ -24,9 +24,10 @@ jobs:
           echo "safe_title=$ESCAPED_TITLE" >> "$GITHUB_OUTPUT"
 
       - name: Post to a Slack channel
-        uses: slackapi/slack-github-action@6c661ce58804a1a20f6dc5fbee7f0381b469e001 # v1.25.0
+        uses: slackapi/slack-github-action@91efab103c0de0a537f72a35f6b8cda0ee76bf0a # v2.1.1
         with:
-          channel-id: eng-execution-mrs
-          slack-message: ":github: `${{ github.repository }}` <${{ github.event.pull_request.html_url }}|${{ steps.sanitize.outputs.safe_title }}>"
-        env:
-          SLACK_BOT_TOKEN: ${{ secrets.SLACK_API_TOKEN }}
+          method: chat.postMessage
+          token: ${{ secrets.SLACK_API_TOKEN }}
+          payload: |
+            channel: eng-execution-mrs
+            text: ":github: `${{ github.repository }}` <${{ github.event.pull_request.html_url }}|${{ steps.sanitize.outputs.safe_title }}>"