Add Cypress Notifier task to Workflow

* This will route the result of the Cypress tests into a Slack channel

.github/workflows/cypress-tests.yml

@@ -15,6 +15,8 @@ on:
         required: true
       SIGNIN_URL:
         required: true
+      SLACK_WEBHOOK_URL:
+        required: true
   workflow_dispatch:
     inputs:
       environment:
@@ -57,3 +59,9 @@ jobs:
         with:
           name: screenshots
           path: Dfe.Academies.External.Web/CypressTests/cypress/screenshots
+
+      - name: Report results
+        if: always()
+        run: npm run cy:notify -- --custom-text="Environment ${{ inputs.environment }}, See more information https://github.com/DFE-Digital/Dfe.Academies.External/actions/runs/${{github.run_id}}"
+        env:
+          SLACK_WEBHOOK_URL: ${{ secrets.SLACK_WEBHOOK_URL }}