use pull_request event rather than workflow_run (#2308)

* use pull_request event rather than workflow_run

* use default for enable-pull-request-comment and enable-commit-comment

.github/workflows/netlify-pr.yaml

@@ -28,7 +28,7 @@ jobs:
           step: start
           token: ${{ secrets.GITHUB_TOKEN }}
           env: Netlify
-          ref: ${{ github.event.workflow_run.head_sha }}
+          ref: ${{ github.ref || github.head_ref }}
           desc: |
             Do you trust the author of this PR? Maybe this build will steal your keys or give you malware.
             Exercise caution. Use test accounts.
@@ -36,8 +36,8 @@ jobs:
       - id: prdetails
         uses: matrix-org/pr-details-action@v1.3
         with:
-          owner: ${{ github.event.workflow_run.head_repository.owner.login }}
-          branch: ${{ github.event.workflow_run.head_branch }}
+          owner: ${{ github.event.pull_request.head.repo.owner.login }}
+          branch: ${{ github.event.pull_request.head.ref }}
 
       - name: 📥 Download artifact
         uses: actions/download-artifact@v4
@@ -50,7 +50,7 @@ jobs:
         run: curl -s https://raw.githubusercontent.com/element-hq/element-call/main/config/netlify_redirects > webapp/_redirects
 
       - name: Add config file
-        run: curl -s "https://raw.githubusercontent.com/${{ github.event.workflow_run.head_repository.full_name }}/${{ github.event.workflow_run.head_branch }}/config/element_io_preview.json" > webapp/config.json
+        run: curl -s "https://raw.githubusercontent.com/${{ github.event.pull_request.head.repo.full_name }}/${{ github.event.pull_request.head.ref }}/config/element_io_preview.json" > webapp/config.json
 
       - name: ☁️ Deploy to Netlify
         id: netlify
@@ -58,9 +58,6 @@ jobs:
         with:
           publish-dir: webapp
           deploy-message: "Deploy from GitHub Actions"
-          # These don't work because we're in workflow_run
-          enable-pull-request-comment: false
-          enable-commit-comment: false
           alias: pr${{ steps.prdetails.outputs.pr_id }}
         env:
           NETLIFY_AUTH_TOKEN: ${{ secrets.NETLIFY_AUTH_TOKEN }}