Really try to fix trigger for deployment job

The deploy job was running against the feature branch instead of
master when the PR is merged.

.github/workflows/hugo.yaml

@@ -11,6 +11,9 @@ on:
       - synchronize
     branches:
       - master
+  push:
+    branches:
+      - master
 
   # Allows you to run this workflow manually from the Actions tab
   workflow_dispatch:
@@ -74,7 +77,8 @@ jobs:
 
   # Deployment job
   deploy:
-    if: ${{ github.event.pull_request.merged }}
+    if: |
+      github.event.push.ref == 'refs/heads/master'
     environment:
       name: github-pages
       url: ${{ steps.deployment.outputs.page_url }}