[CI] Fix syntax error in slack notifications script (#30660)

.github/workflows/rerun-workflows.yml

@@ -30,10 +30,6 @@ jobs:
             const MAX_ATTEMPTS = 2;
             const ATTEMPT = ${{ github.event.workflow_run.run_attempt }};
 
-            const author = `@${context.actor}`;
-            const breaking_commit = context.sha;
-            const branch = context.ref;
-
             if (ATTEMPT <= MAX_ATTEMPTS) {
               github.rest.actions.reRunWorkflowFailedJobs({
                 owner: context.repo.owner,
@@ -42,9 +38,13 @@ jobs:
               });
             } else {
               // notify slack of repeated failure
-              const WebClient = require('@slack/web-api');
+              const { WebClient } = require('@slack/web-api');
               const slack = new WebClient('${{ secrets.SLACK_BOT_TOKEN }}');
 
+              const author = `@${context.actor}`;
+              const breaking_commit = context.sha;
+              const branch = context.ref;
+
               await slack.chat.postMessage({
                 channel: 'engineering-ci',
                 blocks: [