Fix slack action for v3

Author: elelaysh

.github/workflows/multinode.yml

@@ -460,18 +460,16 @@ jobs:
       - name: Send message to Slack via Workflow Builder
         uses: slackapi/slack-github-action@af78098f536edbc4de71162a307590698245be95  # v3.0.1
         with:
+          errors: true
           payload: |
-            {
-              "channel-id": "${{ env.SLACK_CHANNEL_ID }}",
-              "inputs": "${{ env.INPUTS }}",
-              "message": "${{ env.MESSAGE }}",
-              "results-url": "${{ env.RESULTS_URL }}",
-              "workflow-url": "${{ env.WORKFLOW_URL }}"
-            }
+            channel: C03B28HRP53  # #release-train-alerts
+            inputs: "${{ env.INPUTS }}"
+            message: "${{ env.MESSAGE }}"
+            results-url: "${{ env.RESULTS_URL }}"
+            workflow-url: "${{ env.WORKFLOW_URL }}"
+          webhook: ${{ secrets.SLACK_WEBHOOK_URL }}
+          webhook-type: incoming-webhook
         env:
-          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}
-          # #release-train-alerts
-          SLACK_CHANNEL_ID: C03B28HRP53
           INPUTS: >-
             name: ${{ inputs.multinode_name }}\n
             controllers: ${{ inputs.multinode_controller_count }}\n