Drop PR trigger

The git push at the end didn't have permission to push back to the source repo, even if the PR author granted permission for contributors to push to the source branch.

.github/workflows/render.yml

@@ -5,9 +5,6 @@ on:
   push:
     branches:
     - main
-  pull_request:
-    branches:
-    - main
 
 jobs:
 
@@ -16,14 +13,6 @@ jobs:
     steps:
       - name: Checkout repository
         uses: actions/checkout@v4.1.1
-        if: github.event_name != 'pull_request'
-
-      - name: Checkout repo for PR
-        uses: actions/checkout@v4.1.1
-        with:
-          repository: ${{ github.event.pull_request.head.repo.full_name }}
-          ref: ${{ github.event.pull_request.head.ref }}
-        if: github.event_name == 'pull_request'
 
       - name: Compile ZIPs and Zcash Protocol Specification
         uses: ./.github/actions/render