Added Slack notification

Author: CharlesDuboisSAP

.github/workflows/spec-update.yaml

@@ -212,3 +212,16 @@ jobs:
         run: |
           echo "Client generation failed. Please check the Generate step logs for details."
           exit 1
+
+      - name: "Slack Notification"
+        if: failure() && ${{ github.event.inputs.create-pr }}
+        uses: slackapi/[email protected]
+        with:
+          webhook: ${{ secrets.SLACK_WEBHOOK }}
+          webhook-type: incoming-webhook
+          payload: |
+            blocks:
+              - type: "section"
+                text:
+                    type: "mrkdwn"
+                    text: "⚠️ Weekly spec update failed! 😬 Please inspect & fix by clicking <https://github.com/SAP/ai-sdk-java/actions/runs/${{ github.run_id }}|here>"