[WIFI-4884] Add: notification on CI failure in Slack

Signed-off-by: Dmitry Dunaev <dmitry@opsfleet.com>

.github/workflows/ci.yml

@@ -39,6 +39,15 @@ jobs:
         registry_user: ucentral
         registry_password: ${{ secrets.DOCKER_REGISTRY_PASSWORD }}
 
+    - name: Notify on failure via Slack
+      if: failure() && github.ref == 'refs/heads/main'
+      uses: rtCamp/action-slack-notify@v2
+      env:
+        SLACK_USERNAME: GitHub Actions failure notifier
+        SLACK_WEBHOOK: ${{ secrets.SLACK_WEBHOOK }}
+        SLACK_COLOR: "${{ job.status }}"
+        SLACK_ICON: https://raw.githubusercontent.com/quintessence/slack-icons/master/images/github-logo-slack-icon.png
+
   trigger-testing:
     if: startsWith(github.ref, 'refs/pull/')
     runs-on: ubuntu-latest