remove slack announcement

it is now posted using our github webhook

Author: arosiclair

.github/workflows/preDeploy.yml

@@ -27,12 +27,6 @@ jobs:
     steps:
       - uses: actions/checkout@8ade135a41bc03ea155e62e844d188df1ea18608 # v4
 
-      - name: Announce failed workflow in Slack
-        if: ${{ needs.typecheck.result == 'failure' || needs.lint.result == 'failure' || needs.test.result == 'failure' }}
-        uses: ./.github/actions/composite/announceFailedWorkflowInSlack
-        with:
-          SLACK_WEBHOOK: ${{ secrets.SLACK_WEBHOOK }}
-
       - name: Exit failed workflow
         if: ${{ needs.typecheck.result == 'failure' || needs.lint.result == 'failure' || needs.test.result == 'failure' }}
         run: |