chore: enhance publish workflow

Author: openscript

.changeset/tasty-bears-do.md

@@ -0,0 +1,5 @@
+---
+"openscript-ch-website": patch
+---
+
+Use pull request target to trigger deployment

.github/workflows/publish.yaml

@@ -1,15 +1,15 @@
 name: Publish
 
 on:
-  pull_request:
+  pull_request_target:
     types:
       - closed
     branches:
       - master
 
 jobs:
   publish:
-    if: github.event.pull_request.merged == true && github.head_ref == 'changeset-release/master'
+    if: github.event.pull_request.merged == true && github.event.pull_request.head.ref == 'changeset-release/master'
     name: Publish
     runs-on: ubuntu-latest
     steps: