Add: better slack msg

.github/actions/slack-notify/action.yml

@@ -94,5 +94,5 @@ runs:
           thread_ts: "${{ inputs.thread_ts }}"
           text: |
             ❌ Build pipeline failed
-            Is blocked by channel topic: ${{ inputs.blocked || "n/a" }}
+            ${{ inputs.blocked == 'true' && format('Is blocked by channel topic: {0}', inputs.blocked) }}
             • Check logs: <${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}|View details>