Add depoy workflow to prod as well

Turns out it doesn't execute from main even though from what I can tell
it's supposed to. So add a copy to the prod branch, and we'll need to
keep these in sync. Hopefully easy as it shouldn't change much.

Author: mhagander

.github/workflows/deploy.yaml

@@ -0,0 +1,16 @@
+name: Deploy
+
+on:
+  push:
+    branches:
+      - main
+      - prod
+
+jobs:
+  deployment:
+    runs-on: ubuntu-latest
+    environment: ${{ github.ref_name }}
+    steps:
+      - name: Trigger deploy
+        run: |
+          curl -fsS -X POST ${{ secrets.HOOKURL }} -H "X-Key: ${{ secrets.HOOKSECRET }}"