Fix syntax error

Author: iluuu1994

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

@@ -8,5 +8,6 @@ jobs:
     runs-on: ubuntu-latest
     if: ${{ github.repository == 'php/php-src' && github.event.workflow_run.conclusion == 'failure' }}
     steps:
-      - run: >-
-        curl -X POST -H 'Content-type: application/json' --data '{"attachments": [{"text": "Job in *nightly* failed", "footer": "<${{ github.event.workflow_run.jobs_url }}|View Run>", "color": "danger", "mrkdwn_in": ["text"]}]}' ${{ secrets.ACTION_MONITORING_SLACK }}
+      -
+        run: >-
+          curl -X POST -H 'Content-type: application/json' --data '{"attachments": [{"text": "Job in *nightly* failed", "footer": "<${{ github.event.workflow_run.jobs_url }}|View Run>", "color": "danger", "mrkdwn_in": ["text"]}]}' ${{ secrets.ACTION_MONITORING_SLACK }}