Add notification job

Author: aure

.github/workflows/tests.yml

@@ -14,4 +14,12 @@ jobs:
     with:
       scheme: SoundpipeAudioKit
       platforms: iOS macOS
-      swift-versions: 5.5 5.6
+      swift-versions: 5.5 5.6
+
+  # Send notification to Discord on failure.
+  send_notification:
+    name: Send Notification
+    uses: AudioKit/ci/.github/workflows/send_notification.yml@main
+    needs: [swift_test]
+    if: ${{ failure() && github.ref == 'refs/heads/main' }}
+    secrets: inherit